The ring_buffer_discard_commit is similar to ring_buffer_event_discard
but it can only be done on an event that has yet to be commited.
Unpredictable results can happen otherwise.
The main difference between ring_buffer_discard_commit and
ring_buffer_event_discard is that ring_buffer_discard_commit will try
to free the data in the ring buffer if nothing has addded data
after the reserved event. If something did, then it acts almost the
same as ring_buffer_event_discard followed by a
ring_buffer_unlock_commit.
Note, either ring_buffer_commit_discard and ring_buffer_unlock_commit
can be called on an event, not both.
This commit also exports both discard functions to be usable by
GPL modules.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Frederic Weisbecker suggested that the trace_special event shouldn't be
filterable; this patch adds a TRACE_EVENT_FORMAT_NOFILTER event macro
that allows an event format to be exported without having a filter
attached, and removes filtering from the trace_special event.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds run-time field descriptions to all the event formats
exported using TRACE_EVENT_FORMAT. It also hooks up all the tracers
that use them (i.e. the tracers in the 'ftrace subsystem') so they can
also have their output filtered by the event-filtering mechanism.
When I was testing this, there were a couple of things that fooled me
into thinking the filters weren't working, when actually they were -
I'll mention them here so others don't make the same mistakes (and file
bug reports. ;-)
One is that some of the tracers trace multiple events e.g. the
sched_switch tracer uses the context_switch and wakeup events, and if
you don't set filters on all of the traced events, the unfiltered output
from the events without filters on them can make it look like the
filtering as a whole isn't working properly, when actually it is doing
what it was asked to do - it just wasn't asked to do the right thing.
The other is that for the really high-volume tracers e.g. the function
tracer, the volume of filtered events can be so high that it pushes the
unfiltered events out of the ring buffer before they can be read so e.g.
cat'ing the trace file repeatedly shows either no output, or once in
awhile some output but that isn't there the next time you read the
trace, which isn't what you normally expect when reading the trace file.
If you read from the trace_pipe file though, you can catch them before
they disappear.
Changes from v1:
As suggested by Frederic Weisbecker:
- get rid of externs in functions
- added unlikely() to filter_check_discard()
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Before patch:
# tracer: power
#
# TASK-PID CPU# TIMESTAMP FUNCTION
# | | | | |
[ 676.875865889] CSTATE: Going to C1 on cpu 0 for 0.005911463
[ 676.882938805] CSTATE: Going to C1 on cpu 0 for 0.104796532
...
After patch:
# tracer: power
#
# TIMESTAMP STATE EVENT
# | | |
[ 676.875865889] CSTATE: Going to C1 on cpu 0 for 0.005911463
[ 676.882938805] CSTATE: Going to C1 on cpu 0 for 0.104796532
...
v2: Use seq_puts instead of seq_printf
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <49E2E889.5000903@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
BLK_TC_PC events should be treated differently with BLK_TC_FS events.
Before this patch:
# echo 1 > /sys/block/sda/sda1/trace/enable
# echo pc > /sys/block/sda/sda1/trace/act_mask
# echo blk > /debugfs/tracing/current_tracer
# (generate some BLK_TC_PC events)
# cat trace
bash-2184 [000] 1774.275413: 8,7 I N [bash]
bash-2184 [000] 1774.275435: 8,7 D N [bash]
bash-2184 [000] 1774.275540: 8,7 I R [bash]
bash-2184 [000] 1774.275547: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275580: 8,7 C N 0 [0]
bash-2184 [000] 1774.275648: 8,7 I R [bash]
bash-2184 [000] 1774.275653: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275682: 8,7 C N 0 [0]
bash-2184 [000] 1774.275739: 8,7 I R [bash]
bash-2184 [000] 1774.275744: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275771: 8,7 C N 0 [0]
bash-2184 [000] 1774.275804: 8,7 I R [bash]
bash-2184 [000] 1774.275808: 8,7 D R [bash]
ksoftirqd/0-4 [000] 1774.275836: 8,7 C N 0 [0]
After this patch:
# cat trace
bash-2263 [000] 366.782149: 8,7 I N 0 (00 ..) [bash]
bash-2263 [000] 366.782323: 8,7 D N 0 (00 ..) [bash]
bash-2263 [000] 366.782557: 8,7 I R 8 (25 00 ..) [bash]
bash-2263 [000] 366.782560: 8,7 D R 8 (25 00 ..) [bash]
ksoftirqd/0-4 [000] 366.782582: 8,7 C N (25 00 ..) [0]
bash-2263 [000] 366.782648: 8,7 I R 8 (5a 00 3f 00) [bash]
bash-2263 [000] 366.782650: 8,7 D R 8 (5a 00 3f 00) [bash]
ksoftirqd/0-4 [000] 366.782669: 8,7 C N (5a 00 3f 00) [0]
bash-2263 [000] 366.782710: 8,7 I R 8 (5a 00 08 00) [bash]
bash-2263 [000] 366.782713: 8,7 D R 8 (5a 00 08 00) [bash]
ksoftirqd/0-4 [000] 366.782730: 8,7 C N (5a 00 08 00) [0]
bash-2263 [000] 366.783375: 8,7 I R 36 (5a 00 08 00) [bash]
bash-2263 [000] 366.783379: 8,7 D R 36 (5a 00 08 00) [bash]
ksoftirqd/0-4 [000] 366.783404: 8,7 C N (5a 00 08 00) [0]
This is what we do with PC events in user-space blktrace.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D32387.9040106@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Not all events are pc (packet command) events. An event is a pc
event only if it has BLK_TC_PC bit set.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49D3236D.3090705@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: refactor code for future changes
Current kmemtrace.h is used both as header file of kmemtrace and kmem's
tracepoints definition.
Tracepoints' definition file may be used by other code, and should only have
definition of tracepoint.
We can separate include/trace/kmemtrace.h into 2 files:
include/linux/kmemtrace.h: header file for kmemtrace
include/trace/kmem.h: definition of kmem tracepoints
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Acked-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <49DEE68A.5040902@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
- propagate return value of filter_add_pred() to the user
- return -ENOSPC but not -ENOMEM or -EINVAL when the filter array
is full
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04CF0.3010105@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Make sure messages from user space are NIL-terminated strings,
otherwise we could dump random memory while reading filter file.
Try this:
# echo 'parent_comm ==' > events/sched/sched_process_fork/filter
# cat events/sched/sched_process_fork/filter
parent_comm == �
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49E04C32.6060508@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When moving documents to Documentation/trace/, I forgot to
grep Kconfig to find out those references.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Pekka Paalanen <pq@iki.fi>
Cc: eduard.munteanu@linux360.ro
LKML-Reference: <49DE97EF.7080208@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge reason: pick up both v2.6.30-rc1 [which includes tracing/urgent fixes]
and pick up the current lineup of tracing/urgent fixes as well
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I got these from strace:
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 12288
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 16384
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
splice(0x3, 0, 0x5, 0, 0x1000, 0x1) = 8192
I wanted to splice_read 4096 bytes, but it returns 8192 or larger.
It is because the return value of tracing_buffers_splice_read()
does not include "zero out any left over data" bytes.
But tracing_buffers_read() includes these bytes, we make them
consistent.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46674.9030804@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Cleanup
These two lines:
if (unlikely(*ppos))
return -ESPIPE;
in tracing_buffers_splice_read() are not needed, VFS layer
has disabled seek(2).
We remove these two lines, and then we can update file->f_pos.
And tracing_buffers_read() updates file->f_pos, this fix
make tracing_buffers_splice_read() updates file->f_pos too.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46670.4010503@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Cleanup
Sometimes, we open trace_pipe_raw, but we don't read(2) it,
we just splice(2) it, thus, the page is not used.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D4666B.4010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: disable pread()
We set tracing_buffers_fops.llseek to no_llseek,
but we can still perform pread() to read this file.
That is not expected.
This fix uses nonseekable_open() to disable it.
tracing_buffers_fops.llseek is still set to no_llseek,
it mark this file is a "non-seekable device" and is used by
sys_splice(). See also do_splice() or manual of splice(2):
ERRORS
EINVAL Target file system doesn't support splicing;
neither of the descriptors refers to a pipe;
or offset given for non-seekable device.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49D46668.8030806@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix kfree crash with non-standard act_mask string
If passing a string with leading white spaces to strstrip(),
the returned ptr != the original ptr.
This bug was introduced by me.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49DD694C.8020902@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix build warnings and possibe compat misbehavior on IA64
Building a kernel on ia64 might trigger these ugly build warnings:
CC arch/ia64/ia32/sys_ia32.o
In file included from arch/ia64/ia32/sys_ia32.c:55:
arch/ia64/ia32/ia32priv.h:290:1: warning: "elf_check_arch" redefined
In file included from include/linux/elf.h:7,
from include/linux/module.h:14,
from include/linux/ftrace.h:8,
from include/linux/syscalls.h:68,
from arch/ia64/ia32/sys_ia32.c:18:
arch/ia64/include/asm/elf.h:19:1: warning: this is the location of the previous definition
[...]
sys_ia32.c includes linux/syscalls.h which in turn includes linux/ftrace.h
to import the syscalls tracing prototypes.
But including ftrace.h can pull too much things for a low level file,
especially on ia64 where the ia32 private headers conflict with higher
level headers.
Now we isolate the syscall tracing headers in their own lightweight file.
Reported-by: Tony Luck <tony.luck@intel.com>
Tested-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Tony Luck <tony.luck@intel.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Jason Baron <jbaron@redhat.com>
Cc: "Frank Ch. Eigler" <fche@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Jiaying Zhang <jiayingz@google.com>
Cc: Michael Rubin <mrubin@google.com>
Cc: Martin Bligh <mbligh@google.com>
Cc: Michael Davidson <md@google.com>
LKML-Reference: <20090408184058.GB6017@nowhere>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
branch tracer, intel-iommu: fix build with CONFIG_BRANCH_TRACER=y
branch tracer: Fix for enabling branch profiling makes sparse unusable
ftrace: Correct a text align for event format output
Update /debug/tracing/README
tracing/ftrace: alloc the started cpumask for the trace file
tracing, x86: remove duplicated #include
ftrace: Add check of sched_stopped for probe_sched_wakeup
function-graph: add proper initialization for init task
tracing/ftrace: fix missing include string.h
tracing: fix incorrect return type of ns2usecs()
tracing: remove CALLER_ADDR2 from wakeup tracer
blktrace: fix pdu_len when tracing packet command requests
blktrace: small cleanup in blk_msg_write()
blktrace: NUL-terminate user space messages
tracing: move scripts/trace/power.pl to scripts/tracing/power.pl
Unify sched_switch and sched_wakeup's action to following logic:
Do record_cmdline when start_cmdline_record() is called.
Start tracing events when the tracer is started.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <49D1C596.5050203@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Impact: cleanup
The variable ftrace_graph_active is only modified under the
ftrace_lock mutex, thus an atomic is not necessary for modification.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Impact: cleanup
Most of the tracing files creation follow the same pattern:
ret = debugfs_create_file(...)
if (!ret)
pr_warning("Couldn't create ... entry\n")
Unify it!
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238109938-11840-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Impact: cleanup
Use USEC_PER_SEC and NSEC_PER_SEC instead of 1000000 and 1000000000.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <49CC7870.9000309@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Some of the tracers have been renamed, which was not updated in the in-kernel
run-time README file. Update it.
Signed-off-by: Nikanth Karthikesan <knikanth@suse.de>
LKML-Reference: <200903231158.32151.knikanth@suse.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix a crash while cat trace file
Currently we are using a cpumask to remind each cpu where a
trace occured. It lets us notice the user that a cpu just had
its first trace.
But on latest -tip we have the following crash once we cat the trace
file:
IP: [<c0270c4a>] print_trace_fmt+0x45/0xe7
*pde = 00000000
Oops: 0000 [#1] PREEMPT SMP
last sysfs file: /sys/class/net/eth0/carrier
Pid: 3897, comm: cat Not tainted (2.6.29-tip-02825-g0f22972-dirty #81)
EIP: 0060:[<c0270c4a>] EFLAGS: 00010297 CPU: 0
EIP is at print_trace_fmt+0x45/0xe7
EAX: 00000000 EBX: 00000000 ECX: c12d9e98 EDX: ccdb7010
ESI: d31f4000 EDI: 00322401 EBP: d31f3f10 ESP: d31f3efc
DS: 007b ES: 007b FS: 00d8 GS: 00e0 SS: 0068
Process cat (pid: 3897, ti=d31f2000 task=d3b3cf20 task.ti=d31f2000)
Stack:
d31f4080 ccdb7010 d31f4000 d691fe70 ccdb7010 d31f3f24 c0270e5c d31f4000
d691fe70 d31f4000 d31f3f34 c02718e8 c12d9e98 d691fe70 d31f3f70 c02bfc33
00001000 09130000 d3b46e00 d691fe98 00000000 00000079 00000001 00000000
Call Trace:
[<c0270e5c>] ? print_trace_line+0x170/0x17c
[<c02718e8>] ? s_show+0xa7/0xbd
[<c02bfc33>] ? seq_read+0x24a/0x327
[<c02bf9e9>] ? seq_read+0x0/0x327
[<c02ab18b>] ? vfs_read+0x86/0xe1
[<c02ab289>] ? sys_read+0x40/0x65
[<c0202d8f>] ? sysenter_do_call+0x12/0x3c
Code: 00 00 00 89 45 ec f7 c7 00 20 00 00 89 55 f0 74 4e f6 86 98 10 00 00 02 74 45 8b 86 8c 10 00 00 8b 9e a8 10 00 00 e8 52 f3 ff ff <0f> a3 03 19 c0 85 c0 75 2b 8b 86 8c 10 00 00 8b 9e a8 10 00 00
EIP: [<c0270c4a>] print_trace_fmt+0x45/0xe7 SS:ESP 0068:d31f3efc
CR2: 0000000000000000
---[ end trace aa9cf38e5ebed9dd ]---
This is because we alloc the iter->started cpumask on tracing_pipe_open but
not on tracing_open.
It hadn't been noticed until now because we need to have ring buffer overruns
to activate the starting of cpu buffer detection.
Also, we need a check to not print the messagge for the first trace on the file.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238619188-6109-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The wakeup tracing in sched_switch does not stop when a user
disables tracing. This is because the probe_sched_wakeup() is missing
the check to prevent the wakeup from being traced.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
LKML-Reference: <49D1C543.3010307@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Building a kernel with tracing can raise the following warning on
tip/master:
kernel/trace/trace.c:1249: error: implicit declaration of function 'vbin_printf'
We are missing an include to string.h
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1238160130-7437-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix time output bug in 32bits system
ns2usecs() returns 'long', it's incorrect.
(In i386)
...
<idle>-0 [000] 521.442100: _spin_lock <-tick_do_update_jiffies64
<idle>-0 [000] 521.442101: do_timer <-tick_do_update_jiffies64
<idle>-0 [000] 521.442102: update_wall_time <-do_timer
<idle>-0 [000] 521.442102: update_xtime_cache <-update_wall_time
....
(It always print the time less than 2200 seconds besides ...)
Because 'long' is 32bits in i386. ( (1<<31) useconds is about 2200 seconds)
...
<idle>-0 [001] 4154502640.134759: rcu_bh_qsctr_inc <-__do_softirq
<idle>-0 [001] 4154502640.134760: _local_bh_enable <-__do_softirq
<idle>-0 [001] 4154502640.134761: idle_cpu <-irq_exit
...
(very large value)
Because 'long' is a signed type and it is 32bits in i386.
Changes in v2:
return 'unsigned long long' instead of 'cycle_t'
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <49D05D10.4030009@cn.fujitsu.com>
Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Maneesh Soni was getting a crash when running the wakeup tracer.
We debugged it down to the recording of the function with the
CALLER_ADDR2 macro. This is used to get the location of the caller
to schedule.
But the problem comes when schedule is called by assmebly. In the case
that Maneesh had, retint_careful would call schedule. But retint_careful
does not set up a proper frame pointer. CALLER_ADDR2 is defined as
__builtin_return_address(2). This produces the following assembly in
the wakeup tracer code.
mov 0x0(%rbp),%rcx <--- get the frame pointer of the caller
mov %r14d,%r8d
mov 0xf2de8e(%rip),%rdi
mov 0x8(%rcx),%rsi <-- this is __builtin_return_address(1)
mov 0x28(%rdi,%rax,8),%rbx
mov (%rcx),%rax <-- get the frame pointer of the caller's caller
mov %r12,%rcx
mov 0x8(%rax),%rdx <-- this is __builtin_return_address(2)
At the reading of 0x8(%rax) Maneesh's machine would take a fault.
The reason is that retint_careful did not set up the return address
and the content of %rax here was zero.
To verify this, I sent Maneesh a patch to create a frame pointer
in retint_careful. He ran the test again but this time he would take
the same type of fault from sysret_careful. The retint_careful was no
longer an issue, but there are other callers that still have issues.
Instead of adding frame pointers for all callers to schedule (in possibly
all archs), it is much safer to simply not use CALLER_ADDR2. This
loses out on knowing what called schedule, but the function tracer
will help there if needed.
Reported-by: Maneesh Soni <maneesh@in.ibm.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Merge reason: this used to be a tracing/blktrace-v2 devel topic still
cooking during the merge window - has propagated to fixes
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The hw-branch-tracer uses debug store functions from an on_each_cpu()
context, which is simply wrong since the functions may sleep.
Add _noirq variants for most functions, which may be called with
interrupts disabled.
Separate per-cpu and per-task tracing and allow per-cpu tracing to be
controlled from any cpu.
Make the hw-branch-tracer use the new debug store interface, synchronize
with hotplug cpu event using get/put_online_cpus(), and remove the
unnecessary spinlock.
Make the ptrace bts and the ds selftest code use the new interface.
Defer the ds selftest.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
Cc: roland@redhat.com
Cc: eranian@googlemail.com
Cc: oleg@redhat.com
Cc: juan.villacis@intel.com
Cc: ak@linux.jf.intel.com
LKML-Reference: <20090403144555.658136000@intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
* 'kmemtrace-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
kmemtrace: trace kfree() calls with NULL or zero-length objects
kmemtrace: small cleanups
kmemtrace: restore original tracing data binary format, improve ABI
kmemtrace: kmemtrace_alloc() must fill type_id
kmemtrace: use tracepoints
kmemtrace, rcu: don't include unnecessary headers, allow kmemtrace w/ tracepoints
kmemtrace, rcu: fix rcupreempt.c data structure dependencies
kmemtrace, rcu: fix rcu_tree_trace.c data structure dependencies
kmemtrace, rcu: fix linux/rcutree.h and linux/rcuclassic.h dependencies
kmemtrace, mm: fix slab.h dependency problem in mm/failslab.c
kmemtrace, kbuild: fix slab.h dependency problem in lib/decompress_unlzma.c
kmemtrace, kbuild: fix slab.h dependency problem in lib/decompress_bunzip2.c
kmemtrace, kbuild: fix slab.h dependency problem in lib/decompress_inflate.c
kmemtrace, squashfs: fix slab.h dependency problem in squasfs
kmemtrace, befs: fix slab.h dependency problem
kmemtrace, security: fix linux/key.h header file dependencies
kmemtrace, fs: fix linux/fdtable.h header file dependencies
kmemtrace, fs: uninline simple_transaction_set()
kmemtrace, fs, security: move alloc_secdata() and free_secdata() to linux/security.h
* 'tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (413 commits)
tracing, net: fix net tree and tracing tree merge interaction
tracing, powerpc: fix powerpc tree and tracing tree interaction
ring-buffer: do not remove reader page from list on ring buffer free
function-graph: allow unregistering twice
trace: make argument 'mem' of trace_seq_putmem() const
tracing: add missing 'extern' keywords to trace_output.h
tracing: provide trace_seq_reserve()
blktrace: print out BLK_TN_MESSAGE properly
blktrace: extract duplidate code
blktrace: fix memory leak when freeing struct blk_io_trace
blktrace: fix blk_probes_ref chaos
blktrace: make classic output more classic
blktrace: fix off-by-one bug
blktrace: fix the original blktrace
blktrace: fix a race when creating blk_tree_root in debugfs
blktrace: fix timestamp in binary output
tracing, Text Edit Lock: cleanup
tracing: filter fix for TRACE_EVENT_FORMAT events
ftrace: Using FTRACE_WARN_ON() to check "freed record" in ftrace_release()
x86: kretprobe-booster interrupt emulation code fix
...
Fix up trivial conflicts in
arch/parisc/include/asm/ftrace.h
include/linux/memory.h
kernel/extable.c
kernel/module.c
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial: (28 commits)
trivial: Update my email address
trivial: NULL noise: drivers/mtd/tests/mtd_*test.c
trivial: NULL noise: drivers/media/dvb/frontends/drx397xD_fw.h
trivial: Fix misspelling of "Celsius".
trivial: remove unused variable 'path' in alloc_file()
trivial: fix a pdlfush -> pdflush typo in comment
trivial: jbd header comment typo fix for JBD_PARANOID_IOFAIL
trivial: wusb: Storage class should be before const qualifier
trivial: drivers/char/bsr.c: Storage class should be before const qualifier
trivial: h8300: Storage class should be before const qualifier
trivial: fix where cgroup documentation is not correctly referred to
trivial: Give the right path in Documentation example
trivial: MTD: remove EOL from MODULE_DESCRIPTION
trivial: Fix typo in bio_split()'s documentation
trivial: PWM: fix of #endif comment
trivial: fix typos/grammar errors in Kconfig texts
trivial: Fix misspelling of firmware
trivial: cgroups: documentation typo and spelling corrections
trivial: Update contact info for Jochen Hein
trivial: fix typo "resgister" -> "register"
...
Impact: output all of packet commands - not just the first 4 / 8 bytes
Since commit d7e3c3249e ("block: add
large command support"), struct request->cmd has been changed from
unsinged char cmd[BLK_MAX_CDB] to unsigned char *cmd.
v1 -> v2: by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
- make sure rq->cmd_len is always intialized, and then we can use
rq->cmd_len instead of BLK_MAX_CDB.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
LKML-Reference: <49D4507E.2060602@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix corrupted blkparse output
Make sure messages from user space are NUL-terminated strings,
otherwise we could dump random memory to the block trace file.
Additionally, I've limited the message to BLK_TN_MAX_MSG-1
characters, because the last character would be stripped by
vscnprintf anyway.
Signed-off-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: "Alan D. Brunelle" <alan.brunelle@hp.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090403122714.GT5178@kernel.dk>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When kmemtrace was ported to ftrace, the marker strings were taken as
an indication of how the traced data was being exposed to the userspace.
However, the actual format had been binary, not text.
This restores the original binary format, while also adding an origin CPU
field (since ftrace doesn't expose the data per-CPU to userspace), and
re-adding the timestamp field. It also drops arch-independent field
sizing where it didn't make sense, so pointers won't always be 64 bits
wide like they used to.
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
LKML-Reference: <161be9ca8a27b432c4a6ab79f47788c4521652ae.1237813499.git.eduard.munteanu@linux360.ro>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix trace output
kmemtrace_alloc() was not filling type_id, which allowed garbage to make
it into tracing data.
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
LKML-Reference: <284dba2732a144849d5aa82258fe0de2ad8dcb0b.1237813499.git.eduard.munteanu@linux360.ro>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kmemtrace now uses tracepoints instead of markers. We no longer need to
use format specifiers to pass arguments.
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
[ folded: Use the new TP_PROTO and TP_ARGS to fix the build. ]
[ folded: fix build when CONFIG_KMEMTRACE is disabled. ]
[ folded: define tracepoints when CONFIG_TRACEPOINTS is enabled. ]
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
LKML-Reference: <ae61c0f37156db8ec8dc0d5778018edde60a92e3.1237813499.git.eduard.munteanu@linux360.ro>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: prevent possible memory leak
The reader page of the ring buffer is special. Although it points
into the ring buffer, it is not part of the actual buffer. It is
a page used by the reader to swap with a page in the ring buffer.
Once the swap is made, the new reader page is again outside the
buffer.
Even though the reader page points into the buffer, it is really
pointing to residual data. Note, this data is used by the reader.
reader page
|
v
(prev) +---+ (next)
+----------| |----------+
| +---+ |
v v
+---+ +---+ +---+
-->| |------->| |------->| |--->
<--| |<-------| |<-------| |<---
+---+ +---+ +---+
^ ^ ^
\ | /
------- Buffer---------
If we perform a list_del_init() on the reader page we will actually remove
the last page the reader swapped with and not the reader page itself.
This will cause that page to not be freed, and thus is a memory leak.
Luckily, the only user of the ring buffer so far is ftrace. And ftrace
will not free its ring buffer after it allocates it. There is no current
possible memory leak. But once there are other users, or if ftrace
dynamically creates and frees its ring buffer, then this would be a
memory leak.
This patch fixes the leak for future cases.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix to permanent disabling of function graph tracer
There should be nothing to prevent a tracer from unregistering a
function graph callback more than once. This can simplify error paths.
But currently, the counter does not account for mulitple unregistering
of the function graph callback. If it happens, the function graph
tracer will be permanently disabled.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix build warning
I passed a const value to trace_seq_putmem(), and I got compile warning.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Many declarations within trace_output.h are missing the 'extern' keyword
in an inconsistent manner. This adds 'extern' where it should be.
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
trace_seq_reserve() allows a caller to reserve space in a trace_seq and
write directly into it. This makes it easier to export binary data to
userspace via the tracing interface, by simply filling in a struct.
Signed-off-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
blk_trace_event_print() and blk_tracer_print_line() share most of the code.
text data bss dec hex filename
8605 393 12 9010 2332 kernel/trace/blktrace.o.orig
text data bss dec hex filename
8555 393 12 8960 2300 kernel/trace/blktrace.o
This patch also prepares for the next patch, that prints out BLK_TN_MESSAGE.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix mixed ioctl and ftrace-plugin blktrace use memory leak
When mixing the use of ioctl-based blktrace and ftrace-based blktrace,
we can leak memory in this way:
# btrace /dev/sda > /dev/null &
# echo 0 > /sys/block/sda/sda1/trace/enable
now we leak bt->dropped_file, bt->msg_file, bt->rchan...
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix mixed ioctl and ftrace-plugin blktrace use refcount bugs
ioctl-based blktrace allocates bt and registers tracepoints when
ioctl(BLKTRACESETUP), and do all cleanups when ioctl(BLKTRACETEARDOWN).
while ftrace-based blktrace allocates/frees bt when:
# echo 1/0 > /sys/block/sda/sda1/trace/enable
and registers/unregisters tracepoints when:
# echo blk/nop > /debugfs/tracing/current_tracer
or
# echo 1/0 > /debugfs/tracing/tracing_enable
The separatation of allocation and registeration causes 2 problems:
1. current user-space blktrace still calls ioctl(TEARDOWN) when
ioctl(SETUP) failed:
# echo 1 > /sys/block/sda/sda1/trace/enable
# blktrace /dev/sda
BLKTRACESETUP: Device or resource busy
^C
and now blk_probes_ref == -1
2. Another way to make blk_probes_ref == -1:
# plugin sdb && mount sdb1
# echo 1 > /sys/block/sdb/sdb1/trace/enable
# remove sdb
This patch does the allocation and registeration when writing
sdaX/trace/enable.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
'what' is used as the index of array what2act, so it can't >= the array size.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently the original blktrace, which is using relay and is used via
ioctl, is broken. You can use ftrace to see the output of blktrace,
but user-space blktrace is unusable.
It's broken by "blktrace: add ftrace plugin"
(c71a896154)
- if (unlikely(bt->trace_state != Blktrace_running))
+ if (unlikely(bt->trace_state != Blktrace_running || !blk_tracer_enabled))
return;
With this patch, both ioctl and ftrace can be used, but of course you
can't use both of them at the same time.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
t1 t2
------ ------
do_blk_trace_setup() do_blk_trace_setup()
if (!blk_tree_root) {
if (!blk_tree_root)
blk_tree_root = create_dir()
blk_tree_root = create_dir();
(now blk_tree_root == NULL)
...
dir = create_dir(name, blk_tree_root);
Due to this race, t1 will create 'dir' in /debugfs but not /debugfs/block.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
I found the timestamp is wrong:
# echo bin > trace_option
# echo blk > current_tracer
# cat trace_pipe | blkparse -i -
8,0 0 0 0.000000000 504 A W ...
...
8,7 1 0 0.008534097 0 C R ...
(should be 8.534097xxx)
user-space blkparse expects the timestamp to be nanosecond.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix crash (hang) when using TRACE_EVENT_FORMAT filter files
filters are only hooked up to the tracepoint events defined using
TRACE_EVENT but not the tracers that use TRACE_EVENT_FORMAT, such
as ftrace.
Do not display the filter files at all for TRACE_EVENT_FORMAT events
for the time being.
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237878882.8339.61.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Show the average time in the function (Time / Hit)
Function Hit Time Avg
-------- --- ---- ---
mwait_idle 51 140326.6 us 2751.503 us
smp_apic_timer_interrupt 47 3517.735 us 74.845 us
schedule 10 2738.754 us 273.875 us
__schedule 10 2732.857 us 273.285 us
hrtimer_interrupt 47 1896.104 us 40.342 us
irq_exit 56 1711.833 us 30.568 us
__run_hrtimer 47 1315.589 us 27.991 us
tick_sched_timer 47 1138.690 us 24.227 us
do_softirq 56 1116.829 us 19.943 us
__do_softirq 56 1066.932 us 19.052 us
do_IRQ 9 926.153 us 102.905 us
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: safer code
The on the fly allocator for the function profiler was to save
memory. But at the expense of stability. Although it survived several
tests, allocating from the function tracer is just too risky, just
to save space.
This patch removes the allocator and simply allocates enough entries
at start up.
Each function gets a profiling structure of 40 bytes. With an average
of 20K functions, and this is for each CPU, we have 800K per online
CPU. This is not too bad, at least for non-embedded.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
"Because when we call ftrace_free_rec we change the rec->ip to point to the
next record in the chain. Something is very wrong if rec->ip >= s &&
rec->ip < e and the record is already free."
"Note, use FTRACE_WARN_ON() macro. This way it shuts down ftrace if it is
hit and helps to avoid further damage later."
-- Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Empty lines separate cpus stat. After previous
fix(trace_stat: keep original order) applied, the empty lines
are displayed at incorrect position.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C9F266.2060706@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: make trace_stat files show items with the original order
trace_stat tracer reverse the items, it makes the output
looks a little ugly.
Example, when we read trace_stat/workqueues, we get cpu#7's stat.
at first, and then cpu#6... cpu#0.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C9F23F.5040307@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: Fix incorrect way using seq_file's API
Use SEQ_START_TOKEN instead of calling ->stat_headers()
int seq_operation->start().
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Steven Rostedt <srostedt@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
LKML-Reference: <49C9EAE5.5070202@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Ingo Molnar suggested clean ups for the profiling code. This patch
makes those updates.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
graph time is the time that a function is executing another function.
Thus if function A calls B, if graph-time is set, then the time for
A includes B. This is the default behavior. But if graph-time is off,
then the time spent executing B is subtracted from A.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: speed enhancement
By making the function profiler record in per cpu data we not only
get better readings, avoid races, we also do not have to take any
locks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If the function graph trace is enabled, the function profiler will
use it to take the timing of the functions.
cat /debug/tracing/trace_stat/functions
Function Hit Time
-------- --- ----
mwait_idle 127 183028.4 us
schedule 26 151997.7 us
__schedule 31 151975.1 us
sys_wait4 2 74080.53 us
do_wait 2 74077.80 us
sys_newlstat 138 39929.16 us
do_path_lookup 179 39845.79 us
vfs_lstat_fd 138 39761.97 us
user_path_at 153 39469.58 us
path_walk 179 39435.76 us
__link_path_walk 189 39143.73 us
[...]
Note the times are skewed due to the function graph tracer not taking
into account schedules.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: reduce size of memory in function profiler
The function profiler originally introduces its counters into the
function records itself. There is 20 thousand different functions on
a normal system, and that is adding 20 thousand counters for profiling
event when not needed.
A normal run of the profiler yields only a couple of thousand functions
executed, depending on what is being profiled. This means we have around
18 thousand useless counters.
This patch rectifies this by moving the data out of the function
records used by dynamic ftrace. Data is preallocated to hold the functions
when the profiling begins. Checks are made during profiling to see if
more recorcds should be allocated, and they are allocated if it is safe
to do so.
This also removes the dependency from using dynamic ftrace, and also
removes the overhead by having it enabled.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: new profiling feature
This patch adds a function profiler. In debugfs/tracing/ two new
files are created.
function_profile_enabled - to enable or disable profiling
trace_stat/functions - the profiled functions.
For example:
echo 1 > /debugfs/tracing/function_profile_enabled
./hackbench 50
echo 0 > /debugfs/tracing/function_profile_enabled
yields:
cat /debugfs/tracing/trace_stat/functions
Function Hit
-------- ---
_spin_lock 10106442
_spin_unlock 10097492
kfree 6013704
_spin_unlock_irqrestore 4423941
_spin_lock_irqsave 4406825
__phys_addr 4181686
__slab_free 4038222
dput 4030130
path_put 4023387
unroll_tree_refs 4019532
[...]
The most hit functions are listed first. Functions that are not
hit are not listed.
This feature depends on and uses dynamic function tracing. When the
function profiling is disabled, no overhead occurs. But it still
takes up around 300KB to hold the data, thus it is not recomended
to keep it enabled for systems low on memory.
When a '1' is echoed into the function_profile_enabled file, the
counters for is function is reset back to zero. Thus you can see what
functions are hit most by different programs.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Currently, if a trace_stat user wants a handle to some private data,
the trace_stat infrastructure does not supply a way to do that.
This patch passes the trace_stat structure to the start function of
the trace_stat code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: cleanup
struct dyn_ftrace::ip has different usages in his lifecycle,
we use union for it. And also for struct dyn_ftrace::flags.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C871BE.3080405@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix PID output under namespaces
When current namespace is not the global namespace,
pid read from set_ftrace_pid is no correct.
# ~/newpid_namespace_run bash
# echo $$
1
# echo 1 > set_ftrace_pid
# cat set_ftrace_pid
3756
Since we write virtual PID to set_ftrace_pid, we need get
virtual PID when we read it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C84D65.9050606@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: give user a choice to show times spent while sleeping
The user may want to see the time a function spent sleeping.
This patch adds the trace option "sleep-time" to allow that.
The "sleep-time" option is default on.
echo sleep-time > /debug/tracing/trace_options
produces:
------------------------------------------
2) avahi-d-3428 => <idle>-0
------------------------------------------
2) | finish_task_switch() {
2) 0.621 us | _spin_unlock_irq();
2) 2.202 us | }
2) ! 1002.197 us | }
2) ! 1003.521 us | }
where as,
echo nosleep-time > /debug/tracing/trace_options
produces:
0) <idle>-0 => yum-upd-3416
------------------------------------------
0) | finish_task_switch() {
0) 0.643 us | _spin_unlock_irq();
0) 2.342 us | }
0) + 41.302 us | }
0) + 42.453 us | }
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: more accurate timings
The current method of function graph tracing does not take into
account the time spent when a task is not running. This shows functions
that call schedule have increased costs:
3) + 18.664 us | }
------------------------------------------
3) <idle>-0 => kblockd-123
------------------------------------------
3) | finish_task_switch() {
3) 1.441 us | _spin_unlock_irq();
3) 3.966 us | }
3) ! 2959.433 us | }
3) ! 2961.465 us | }
This patch uses the tracepoint in the scheduling context switch to
account for time that has elapsed while a task is scheduled out.
Now we see:
------------------------------------------
3) <idle>-0 => edac-po-1067
------------------------------------------
3) | finish_task_switch() {
3) 0.685 us | _spin_unlock_irq();
3) 2.331 us | }
3) + 41.439 us | }
3) + 42.663 us | }
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: prevent crash due to multiple function graph tracers
The function graph tracer can currently only handle a single tracer
being registered. If another tracer registers with the function
graph tracer it can crash the system.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch move the timestamp from happening in the arch specific
code into the general code. This allows for better control by the tracer
to time manipulation.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If the function profiler does not have any items recorded and one were
to cat the function stat file, the kernel would take a BUG with a NULL
pointer dereference.
Looking further into this, I found that returning NULL from stat_start
did not stop the stat logic, and would later call stat_next. This breaks
from the way seq_file works, so I looked into fixing the stat code.
This is where I noticed that the last next_entry is never freed.
It is allocated, and if the stat_next returns NULL, the code breaks out
of the loop, unlocks the mutex and exits. We never link the next_entry
nor do we free it. Thus it is a real memory leak.
This patch rearranges the code a bit to not only fix the memory leak,
but also to act more like seq_file where nothing is printed if there
is nothing to print. That is, stat_start returns NULL.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: new feature, allow symbolic values in /debug/tracing/act_mask
Print stringified act_mask instead of hex value:
# cat act_mask
read,write,barrier,sync,queue,requeue,issue,complete,fs,pc,ahead,meta,
discard,drv_data
# echo "meta,write" > act_mask
# cat act_mask
write,meta
Also:
- make act_mask accept "ahead", "meta", "discard" and "drv_data"
- use strsep() instead of strchr() to parse user input
- return -EINVAL if a token is not found in the mask map
- fix a bug that 'value' is unsigned, so it can < 0
- propagate error value of blk_trace_mask2str() to userspace, but not
always return -ENXIO.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C8AB42.1000802@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix the output of IO type category characters
Trace categories are the upper 16 bits, not the lower 16 bits.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
LKML-Reference: <49C89432.8010805@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix filter use boundary condition / crash
Make sure filters for string fields don't use integer values and vice
versa. Getting it wrong can crash the system or produce bogus
results.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237878882.8339.61.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Instead of just using the trace_seq buffer to print the filters, use
trace_seq_printf() as it was intended to be used.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237878871.8339.59.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix (small) per trace filter modification memory leak
Free the current pred when clearing the filters via the filter files.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237878851.8339.58.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
No need to use the safe version here, so use list_for_each_entry instead
of list_for_each_entry_safe in find_event_field().
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237878841.8339.57.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix traces output
Sometimes one can observe an imbalance in the traces between function
calls and function return traces:
func1() {
}
}
The curly brace inside func1() is the return of another function nested
inside func1. The return trace have been inserted in the buffer but not
the entry.
We are storing a return address on the function traces stack while we
haven't inserted its entry on the buffer, hence the imbalance on the
traces.
This is because the tracers doesn't check all failures that can happen
on buffer insertion.
This patch reports the tracing recursion failures and the ring buffer
failures. In such cases, we now restore the original return address for
the function, giving up its return trace.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237843021-11695-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
commit 40ada30f96 ("tracing: clean up menu"),
despite the "clean up" in its purpose, introduced a behavioural
change for Kconfig symbols: we no longer able to select tracing
support on PPC32 (because IRQFLAGS_SUPPORT isn't yet implemented).
The IRQFLAGS_SUPPORT is not mandatory for most tracers, tracing core
has a special case for platforms w/o irqflags (which, by the way, has
become useless as of the commit above).
Though according to Ingo Molnar, there was periodic build failures on
weird, unmaintained architectures that had no irqflags-tracing support
and hence didn't know the raw_irqs_save/restore primitives. Thus we'd
better not enable irqflags-less tracing for all architectures.
This patch restores the old behaviour for PPC32, and thus brings the
tracing back. Other architectures can either add themselves to the
exception list or (better) implement TRACE_IRQFLAGS_SUPPORT.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Acked-b: Steven Rostedt <rostedt@goodmis.org>
Cc: linuxppc-dev@ozlabs.org
LKML-Reference: <20090323220724.GA9851@oksana.dev.rtsoft.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix a crash with ftrace={nop,boot} parameter
If the nop or initcall tracers are launched as boot tracers,
they will attempt to create their option directory and files.
But these tracers are registered very early and then assigned
as "boot tracers" very early if asked to.
Since they do this before debugfs has been registered (core initcall),
a crash is triggered.
Another early tracers could also come later. So we fix it by
checking if debugfs is initialized before creating the root
tracing directory.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup, memory leak fix
This patch cleans up filter_add_subsystem_pred():
- searches for the field before creating a copy of the pred
- fixes memory leak in the case a predicate isn't applied
- if -ENOMEM, makes sure there's no longer a reference to the
pred so the caller can free the half-finished filter
- changes the confusing i == MAX_FILTER_PRED - 1 comparison
previously remarked upon
This affects only per-subsystem event filtering.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237796808.7527.40.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix potential crash on subsystem filter expression freeing
When making a copy of the predicate, pred->field_name needs to be
duplicated in the copy as well, otherwise bad things can happen due to
later multiple frees of the same string.
This affects only per-subsystem event filtering.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237796802.7527.39.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When we want to filter an event, the filter test is done after
the event is commited to the ring-buffer to be discarded later if
needed.
But a reader could be reading this event while we are trying to discard
it. Other kind of racy events can even happen because the event is
commited and can be read and/or consumed.
What we want is to discard the event before committing it.
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237763919-21505-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: display events when they arrive
Now that the events don't use wake_up() anymore, we need the nop
tracer to poll waiting for events on the pipe. Especially because
nop is useful to look at orphan traces types (traces types that
don't rely on specific tracers) because it doesn't produce traces
itself.
And unlike other tracers that trigger specific traces periodically,
nop triggers no traces by itself that can wake him.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix hard-lockup with sched switch events
Some ftrace events, such as sched wakeup, can be traced
while the runqueue lock is hold. Since they are using
trace_current_buffer_unlock_commit(), they call wake_up()
which can try to grab the runqueue lock too, resulting in
a deadlock.
Now for all event, we call a new helper:
trace_nowake_buffer_unlock_commit() which do pretty the same than
trace_current_buffer_unlock_commit() except than it doesn't call
trace_wake_up().
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237759847-21025-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We need the filter files to be writable, the current
filter file permissions are only set readable.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237759847-21025-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix potential kfree of random data in (rare) failure path
Zero-initialize the field structure.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds per-subsystem filtering to the event tracing subsystem.
It adds a 'filter' debugfs file to each subsystem directory. This file
can be written to to set filters; reading from it will display the
current set of filters set for that subsystem.
Basically what it does is propagate the filter down to each event
contained in the subsystem. If a particular event doesn't have a field
with the name specified in the filter, it simply doesn't get set for
that event. You can verify whether or not the filter was set for a
particular event by looking at the filter file for that event.
As with per-event filters, compound expressions are supported, echoing
'0' to the subsystem's filter file clears all filters in the subsystem,
etc.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710677.7703.49.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds per-event filtering to the event tracing subsystem.
It adds a 'filter' debugfs file to each event directory. This file can
be written to to set filters; reading from it will display the current
set of filters set for that event.
Basically, any field listed in the 'format' file for an event can be
filtered on (including strings, but not yet other array types) using
either matching ('==') or non-matching ('!=') 'predicates'. A
'predicate' can be either a single expression:
# echo pid != 0 > filter
# cat filter
pid != 0
or a compound expression of up to 8 sub-expressions combined using '&&'
or '||':
# echo comm == Xorg > filter
# echo "&& sig != 29" > filter
# cat filter
comm == Xorg
&& sig != 29
Only events having field values matching an expression will be available
in the trace output; non-matching events are discarded.
Note that a compound expression is built up by echoing each
sub-expression separately - it's not the most efficient way to do
things, but it keeps the parser simple and assumes that compound
expressions will be relatively uncommon. In any case, a subsequent
patch introducing a way to set filters for entire subsystems should
mitigate any need to do this for lots of events.
Setting a filter without an '&&' or '||' clears the previous filter
completely and sets the filter to the new expression:
# cat filter
comm == Xorg
&& sig != 29
# echo comm != Xorg
# cat filter
comm != Xorg
To clear a filter, echo 0 to the filter file:
# echo 0 > filter
# cat filter
none
The limit of 8 predicates for a compound expression is arbitrary - for
efficiency, it's implemented as an array of pointers to predicates, and
8 seemed more than enough for any filter...
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710665.7703.48.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch overloads RINGBUF_TYPE_PADDING to provide a way to discard
events from the ring buffer, for the event-filtering mechanism
introduced in a subsequent patch.
I did the initial version but thanks to Steven Rostedt for adding
the parts that actually made it work. ;-)
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup.
This patch fixes the following sparse warnings:
kernel/trace/trace.c:385:9: warning: symbol 'trace_seq_to_buffer' was
not declared. Should it be static?
kernel/trace/trace_clock.c:29:13: warning: symbol 'trace_clock_local'
was not declared. Should it be static?
kernel/trace/trace_clock.c:54:13: warning: symbol 'trace_clock' was not
declared. Should it be static?
kernel/trace/trace_clock.c:74:13: warning: symbol 'trace_clock_global'
was not declared. Should it be static?
Signed-off-by: Dmitri Vorobiev <dmitri.vorobiev@movial.com>
LKML-Reference: <1237741871-5827-4-git-send-email-dmitri.vorobiev@movial.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch makes the field descriptions defined for event tracing
available at run-time, for the event-filtering mechanism introduced
in a subsequent patch.
The common event fields are prepended with 'common_' in the format
display, allowing them to be distinguished from the other fields
that might internally have same name and can therefore be
unambiguously used in filters.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237710639.7703.46.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Instead of using ftrace_dump_on_oops, it's far more convenient
to have the trace leading up to a self-test failure available
in /debug/tracing/trace.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: detect tracing related hangs
Sometimes, with some configs, the function graph tracer can make
the timer interrupt too much slow, hanging the kernel in an endless
loop of timer interrupts servicing.
As suggested by Ingo, this patch brings a watchdog which stops the
selftest after a defined number of functions traced, definitely
disabling this tracer.
For those who want to debug the cause of the function graph trace
hang, you can pass the ftrace_dump_on_oops kernel parameter to dump
the traces after this hang detection.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237694675-23509-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
bdev->bd_disk can be NULL, if the block device is not opened.
Try this against an unmounted partition, and you'll see NULL dereference:
# echo 1 > /sys/block/sda/sda5/enable
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C30098.6080107@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
do_blk_trace_setup() may return EBUSY, but the current code
doesn't decrease blk_probes_ref in this case.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C2F5FF.80002@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
blk_register_tracepoints() always returns 0, so make it return void,
thus we don't need to use blk_probe_mutex to protect blk_probes_ref.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C2F5EA.8060606@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
It doesn't have to be a counter, and it can be a bool flag instead.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <49C2F5D3.8090104@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When we failed to create "block" debugfs dir, we should do some
cleanups.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <49C2F5B2.8000800@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: remove a section warning
CONFIG_DEBUG_SECTION_MISMATCH raises the following warning on -tip:
WARNING: kernel/trace/built-in.o(.text+0x5bc5): Section mismatch in
reference from the function ring_buffer_alloc() to the function
.cpuinit.text:rb_cpu_notify()
The function ring_buffer_alloc() references
the function __cpuinit rb_cpu_notify().
This is actually harmless. The code in the ring buffer don't build
rb_cpu_notify and other cpu hotplug stuffs when !CONFIG_HOTPLUG_CPU
so we have no risk to reference freed memory here (it would even
be harmless if we unconditionally build it because register_cpu_notifier
would do nothing when !CONFIG_HOTPLUG_CPU.
But since ring_buffer_alloc() can be called everytime, we don't want it
to be annotated with __cpuinit so we drop the __cpuinit from
rb_cpu_notify.
This is not a waste of memory because it is only defined and used on
CONFIG_HOTPLUG_CPU.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237606416-22268-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new tracing infrastructure feature
Provide infrastructure to generate software perf counter events
from tracepoints.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.557364871@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: widen user-space visibe event IDs to all events
Previously only TRACE_EVENT events got ids, because only they
generated raw output which needs to be demuxed from the trace.
In order to provide a unique ID for each event, register everybody,
regardless.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.464914218@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Since not every event has a format file to read the id from,
expose it explicitly in a separate file.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <20090319194233.372534033@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
With the added TRACE_EVENT macro, the events no longer appear in
the function graph tracer. This was because the function graph
did not know how to display the entries. The graph tracer was
only aware of its own entries and the printk entries.
By using the event call back feature, the graph tracer can now display
the events.
# echo irq > /debug/tracing/set_event
Which can show:
0) | handle_IRQ_event() {
0) | /* irq_handler_entry: irq=48 handler=eth0 */
0) | e1000_intr() {
0) 0.926 us | __napi_schedule();
0) 3.888 us | }
0) | /* irq_handler_exit: irq=48 return=handled */
0) 0.655 us | runqueue_is_locked();
0) | __wake_up() {
0) 0.831 us | _spin_lock_irqsave();
The irq entry and exit events show up as comments.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The function depth in trace_printk was to facilitate the function
graph output. Now that the function graph calculates the depth within
the trace output, we no longer need to record the depth when the
trace_printk is called.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Currently, the function graph tracer depends on the trace_printk
to record the depth. All the information is already there in the trace
to calculate function depth, with the exception of having the printk
be the first item. But as soon as a entry or exit is reached, then
we know the depth.
This patch changes the iter->private data from recording a per cpu
last_pid, to a structure that holds both the last_pid and the current
depth. This data is used to determine the function depth for the
printks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch makes print_printk_msg_only and print_bprintk_msg_only
global for other functions to use. It also renames them by adding
a "trace_" to the beginning to avoid namespace collisions.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix warning with irqsoff tracer
The ring buffer allocates its buffers on pre-smp time (early_initcall).
It means that, at first, only the boot cpu buffer is allocated and
the ring-buffer cpumask only has the boot cpu set (cpu_online_mask).
Later, the secondary cpu will show up and the ring-buffer will be notified
about this event: the appropriate buffer will be allocated and the cpumask
will be updated.
Unfortunately, if !CONFIG_CPU_HOTPLUG, the ring-buffer will not be
notified about the secondary cpus, meaning that the cpumask will have
only the cpu boot set, and only one cpu buffer allocated.
We fix that by using cpu_possible_mask if !CONFIG_CPU_HOTPLUG.
This patch fixes the following warning with irqsoff tracer running:
[ 169.317794] WARNING: at kernel/trace/trace.c:466 update_max_tr_single+0xcc/0xf3()
[ 169.318002] Hardware name: AMILO Li 2727
[ 169.318002] Modules linked in:
[ 169.318002] Pid: 5624, comm: bash Not tainted 2.6.29-rc8-tip-02636-g6aafa6c #11
[ 169.318002] Call Trace:
[ 169.318002] [<ffffffff81036182>] warn_slowpath+0xea/0x13d
[ 169.318002] [<ffffffff8100b9d6>] ? ftrace_call+0x5/0x2b
[ 169.318002] [<ffffffff8100b9d6>] ? ftrace_call+0x5/0x2b
[ 169.318002] [<ffffffff8100b9d1>] ? ftrace_call+0x0/0x2b
[ 169.318002] [<ffffffff8101ef10>] ? ftrace_modify_code+0xa9/0x108
[ 169.318002] [<ffffffff8106e27f>] ? trace_hardirqs_off+0x25/0x27
[ 169.318002] [<ffffffff8149afe7>] ? _spin_unlock_irqrestore+0x1f/0x2d
[ 169.318002] [<ffffffff81064f52>] ? ring_buffer_reset_cpu+0xf6/0xfb
[ 169.318002] [<ffffffff8106637c>] ? ring_buffer_reset+0x36/0x48
[ 169.318002] [<ffffffff8106aeda>] update_max_tr_single+0xcc/0xf3
[ 169.318002] [<ffffffff8100bc17>] ? sysret_check+0x22/0x5d
[ 169.318002] [<ffffffff8106e3ea>] stop_critical_timing+0x142/0x204
[ 169.318002] [<ffffffff8106e4cf>] trace_hardirqs_on_caller+0x23/0x25
[ 169.318002] [<ffffffff8149ac28>] trace_hardirqs_on_thunk+0x3a/0x3c
[ 169.318002] [<ffffffff8100bc17>] ? sysret_check+0x22/0x5d
[ 169.318002] ---[ end trace db76cbf775a750cf ]---
Because this tracer may try to swap two cpu ring buffers for an
unregistered cpu on the ring buffer.
This patch might also fix a fair loss of traces due to unallocated buffers
for secondary cpus.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-b: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1237470453-5427-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
The prologue of the function graph entry, return and comments all
start out pretty much the same. Each of these duplicate code and
do so slightly differently.
This patch consolidates the printing of the pid, absolute time,
cpu and proc (and for entry, the interrupt).
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
There is currently no easy way to clear the trace buffer. Currently
the only way is to change the current tracer.
This patch lets the user clear the trace buffer by simply writing
into the trace files.
echo > /debug/tracing/trace
or to clear a single cpu (i.e. for CPU 1):
echo > /debug/tracing/per_cpu/cpu1/trace
Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix command line to pid mapping
map_cmdline_to_pid[] is checked in trace_save_cmdline(), but never
updated. This results in stale pid to command line mappings and the
tracer output will associate the wrong comm string.
Signed-off-by: Carsten Emde <Carsten.Emde@osadl.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: prevent stale command line output
In case there is no valid command line mapping for a pid
trace_find_cmdline() returns without updating the comm buffer. The
trace dump keeps the previous entry which results in confusing trace
output:
<idle>-0 [000] 280.702056 ....
<idle>-23456 [000] 280.702080 ....
Update the comm buffer with "<...>" when no mapping is found.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
The command line recorder uses (unsigned) -1 to mark non mapped
entries in the pid to command line maps. The validity check is
completely unintuitive: idx >= SAVED_CMDLINES
There is no need for such casting games. Use a constant to mark
unmapped entries and check for that constant to make the code readable
and understandable.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: prevent overwrite of command line entries
When the tracer is stopped the command line recording continues to
record. The check for tracing_is_on() is not sufficient here as the
ringbuffer status is not affected by setting
debug/tracing/tracing_enabled to 0. On a non idle system this can
result in the loss of the command line information for the stopped
trace, which makes the trace harder to read and analyse.
Check tracer_enabled to allow further recording.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The start/stop methods of a tracer should be able to be executed
in all contexts. This patch converts the power tracer to do so.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The stopping and starting of a tracer should be light weight and
be able to be called in all contexts. The sched_switch grabbed
mutexes in the start/stop functions. This patch changes it to a
simple variable, on/off.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: feature to allow better serialized clock
This patch adds an option called "global-clock" that will allow
the tracer to switch to a slower but more accurate (across CPUs)
clock.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch adds a new function called ring_buffer_set_clock that
allows a tracer to assign its own clock source to the buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix memory leak
If event_format_read() exits early due to nonzero ppos, the
previous kmalloc doesn't get freed - might as well do the
check before the kmalloc and avoid the problem.
Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: =?ISO-8859-1?Q?Fr=E9d=E9ric?= Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237270859.8033.141.camel@charm-linux>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix for losing comms in trace
The command lines of tasks are cached at sched switch to not need
to record them at every trace point. Disabling the tracing on stops
the recording of traces, but does not stop the caching of command lines.
When the tracing is off the cache may overflow and cause the tracing
to show incorrect tasks matching the PIDs.
This patch disables prevents updates to the comm cache when the ring buffer
is off.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to one cause of incorrect comm outputs in trace
The spinlock only protected the creation of a comm <=> pid pair.
But it was possible that a reader could look up a pid, and get the
wrong comm because it had no locking.
This also required changing trace_find_cmdline to copy the comm cache
and not just send back a pointer to it.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix a dynamic tracing failure
Recently, the function and function graph tracers failed to use dynamic
tracing after the following commit:
fa9d13cf13
(ftrace: don't try to __ftrace_replace_code on !FTRACE_FL_CONVERTED rec)
The patch is right except a mistake on the check for the FTRACE_FL_CONVERTED
flag. The code patching is aborted in case of successfully nopped sites.
What we want is the opposite: ignore the callsites that haven't been nopped.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix crashes when tracing cpumasks
While ring-buffer allocation, the cpumasks are allocated too,
including the tracing cpumask and the per-cpu file mask handler.
But these cpumasks are freed accidentally just after.
Fix it.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237164303-11476-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix possible locking imbalance
In case of ring buffer resize failure, tracing_set_tracer forgot to
release trace_types_lock. Fix it.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Syscall tracing must select kallsysms.
The arch code builds a table to find the syscall metadata by syscall
number. It needs the syscalls names resolution from the symbol table
to know which name found on the syscalls metadatas match a function
pointer from the arch sys_call_table.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix syscall tracer enable/disable race
The current thread flag toggling is racy as shown in the following
scenario:
- task A is the last user of syscall tracing, it releases the
TIF_SYSCALL_FTRACE on each tasks
- at the same time task B start syscall tracing. refcount == 0 so
it sets up TIF_SYSCALL_FTRACE on each tasks.
The effect of the mixup is unpredictable.
So this fix adds a mutex on {start,stop}_syscall_tracing().
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1237151439-6755-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix 'stuck' syscall tracer
The syscall tracer uses a refcounter to enable several users
simultaneously.
But the refcounter did not behave correctly and always restored
its value to 0 after calling start_syscall_tracing(). Therefore,
stop_syscall_tracing() couldn't release correctly the tasks from
tracing.
Also the tracer forgot to reset the buffer when it is released.
Drop the pointless refcount decrement on start_syscall_tracing()
and reset the buffer when we release the tracer.
This fixes two reported issue:
- when we switch from syscall tracer to another tracer, syscall
tracing continued.
- incorrect use of the refcount.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1237151439-6755-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: new feature
This adds the generic support for syscalls tracing. This is
currently exploited through a devoted tracer but other tracing
engines can use it. (They just have to play with
{start,stop}_ftrace_syscalls() and use the display callbacks
unless they want to override them.)
The syscalls prototypes definitions are abused here to steal
some metadata informations:
- syscall name, param types, param names, number of params
The syscall addr is not directly saved during this definition
because we don't know if its prototype is available in the
namespace. But we don't really need it. The arch has just to
build a function able to resolve the syscall number to its
metadata struct.
The current tracer prints the syscall names, parameters names
and values (and their types optionally). Currently the value is
a raw hex but higher level values diplaying is on my TODO list.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1236955332-10133-2-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add a selftest for the hw-branch-tracer.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090313105027.A30183@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Distinguish init/reset and start/stop:
init/reset will allocate and release bts tracing resources
stop/start will suspend and resume bts tracing
Return an error on init() if no cpu can be traced.
Signed-off-by: Markus Metzger <markus.t.metzger@intel.com>
LKML-Reference: <20090313104852.A30168@sedona.ch.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: save memory
The struct dyn_ftrace table is very large, this patch will save
about 50%.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2C9F.8020009@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
VFS layer has tested the file mode, we do not need test it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <49BA2BAB.6010608@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Do __ftrace_replace_code for !FTRACE_FL_CONVERTED rec will always
fail, we should ignore this rec.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: "Steven Rostedt ;" <rostedt@goodmis.org>
LKML-Reference: <49BA2472.4060206@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If dyn_ftrace is freed before ftrace_release(), ftrace_release()
will free it again and make ftrace_free_records wrong.
Signed-off-by: Zhao Lei <zhaolei@cn.fujitsu.com>
Cc: "Steven Rostedt ;" <rostedt@goodmis.org>
LKML-Reference: <49BA23D9.1050900@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Provide basic callbacks to do syscall tracing.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <1236401580-5758-2-git-send-email-fweisbec@gmail.com>
[ simplified it to a trace_printk() for now. ]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The binary_buffers directory in /debugfs/tracing held the files
to read the trace buffers in a binary format. This held one file
per CPU buffer. But we also have a per_cpu directory that holds
a way to read the pretty-print formats.
This patch moves the binary buffers into the per_cpu_directory:
# ls /debug/tracing/per_cpu/cpu1/
trace trace_pipe trace_pipe_raw
The new name is called "trace_pipe_raw". The binary buffers always
acted similar to trace_pipe, except that they produce raw data.
Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: documentation
The use of the double __builtin_contant_p checks in the event_trace_printk
can be confusing to developers and reviewers. This patch adds a comment
to explain why it is there.
Requested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20090313122235.43EB.A69D9226@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
In a private email conversation I explained how the ring buffer
page worked by using silly ASCII art. Ingo suggested that I add
that to the comments of the code.
Here it is.
Requested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Unlike TRACE_FORMAT() macros, the TRACE_EVENT() macros do not show
the event name in the trace file. Knowing the event type in the trace
output is very useful.
Instead of:
task swapper:0 [140] ==> ntpd:3308 [120]
We now have:
sched_switch: task swapper:0 [140] ==> ntpd:3308 [120]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
commit c3ffc7a40b
"Don't use tracing_record_cmdline() in workqueue tracer"
has a race window.
find_task_by_vpid() requires task_list_lock().
LKML-Reference: <20090313090042.43CD.A69D9226@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If the stack tracing is disabled (by default) the stack_trace file
will only contain the header:
# cat /debug/tracing/stack_trace
Depth Size Location (0 entries)
----- ---- --------
This can be frustrating to a developer that does not realize that the
stack tracer is disabled. This patch adds the following text:
# cat /debug/tracing/stack_trace
Depth Size Location (0 entries)
----- ---- --------
#
# Stack tracer disabled
#
# To enable the stack tracer, either add 'stacktrace' to the
# kernel command line
# or 'echo 1 > /proc/sys/kernel/stack_tracer_enabled'
#
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The binary printk saves a pointer to the format string in the ring buffer.
On output, the format is processed. But if the user is reading the
ring buffer through a binary interface, the pointer is meaningless.
This patch creates a file called printk_formats that maps the pointers
to the formats.
# cat /debug/tracing/printk_formats
0xffffffff80713d40 : "irq_handler_entry: irq=%d handler=%s\n"
0xffffffff80713d48 : "lock_acquire: %s%s%s\n"
0xffffffff80713d50 : "lock_release: %s\n"
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: speed up on event tracing
The event_trace_printk is currently a wrapper function that calls
trace_vprintk. Because it uses a variable for the fmt it misses out
on the optimization of using the binary printk.
This patch makes event_trace_printk into a macro wrapper to use the
fmt as the same as the trace_printks.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix callsites with dynamic format strings
Since its new binary implementation, trace_printk() internally uses static
containers for the format strings on each callsites. But the value is
assigned once at build time, which means that it can't take dynamic
formats.
So this patch unearthes the raw trace_printk implementation for the callers
that will need trace_printk to be able to carry these dynamic format
strings. The trace_printk() macro will use the appropriate implementation
for each callsite. Most of the time however, the binary implementation will
still be used.
The other impact of this patch is that mmiotrace_printk() will use the old
implementation because it calls the low level trace_vprintk and we can't
guess here whether the format passed in it is dynamic or not.
Some parts of this patch have been written by Steven Rostedt (most notably
the part that chooses the appropriate implementation for each callsites).
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: do not confuse user on small trace buffer sizes
When the system boots up, the trace buffer is small to conserve memory.
It is only two pages per online CPU. When the tracer is used, it expands
to the default value.
This can confuse the user if they look at the buffer size and see only
7, but then later they see 1408.
# cat /debug/tracing/buffer_size_kb
7
# echo sched_switch > /debug/tracing/current_tracer
# cat /debug/tracing/buffer_size_kb
1408
This patch tries to help remove this confustion by showing that the
buffer has not been expanded.
# cat /debug/tracing/buffer_size_kb
7 (expanded: 1408)
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: speed up and remove possible races
The get_online_cpus was added to the ring buffer because the original
design would free the ring buffer on a CPU that was being taken
off line. The final design kept the ring buffer around even when the
CPU was taken off line. This is to allow a user to still read the
information on that ring buffer.
Most of the get_online_cpus are no longer needed since the ring buffer will
not disappear from the use cases.
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The hotplug code in the ring buffers is for use with CPU hotplug,
not generic hotplug.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: prevent races with ring_buffer_expanded
This patch places the expanding of the tracing buffer under the
protection of the trace_types_lock mutex. It is highly unlikely
that there would be any contention, but better safe than sorry.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: cleanup
Some of the comments about the trace buffer resizing is gobbledygook.
And I wonder why people question if I'm a native English speaker.
This patch makes the comments make a bit more sense.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: save on memory
Currently, a ring buffer was allocated for each "possible_cpus". On
some systems, this is the same as NR_CPUS. Thus, if a system defined
NR_CPUS = 64 but it only had 1 CPU, we could have possibly 63 useless
ring buffers taking up space. With a default buffer of 3 megs, this
could be quite drastic.
This patch changes the ring buffer code to only allocate ring buffers
for online CPUs. If a CPU goes off line, we do not free the buffer.
This is because the user may still have trace data in that buffer
that they would like to look at.
Perhaps in the future we could add code to delete a ring buffer if
the CPU is offline and the ring buffer becomes empty.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to task live locking on reading trace_pipe on one CPU
The same code is used for both trace_pipe (all CPUS) and the per_cpu
trace_pipe file. When there is no data to read, it will check for
signals and wait on the trace wait queue.
The problem happens with the per_cpu wait. The trace_wait code checks
all CPUs. Thus, if there's data in another CPU buffer, then it will
exit the wait, without checking for signals or waiting on the wait queue.
It would then try to read the empty buffer, and since that will just
return nothing, then it will try to wait again. Unfortunately, that will
again fail due to there still being data in the other buffers. This
ends up with a live lock for the task.
This patch fixes the trace_wait to be aware that the iterator may only
be waiting on a single buffer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
To save memory, the tracer ring buffers are set to a minimum.
The activating of a trace expands the ring buffer size. This patch
adds this expanding, when an event is activated.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: less memory impact on systems not using tracer
When the kernel boots up that has tracing configured, it allocates
the default size of the ring buffer. This currently happens to be
1.4Megs per possible CPU. This is quite a bit of wasted memory if
the system is never using the tracer.
The current solution is to keep the ring buffers to a minimum size
until the user uses them. Once a tracer is piped into the current_tracer
the ring buffer will be expanded to the default size. If the user
changes the size of the ring buffer, it will take the size given
by the user immediately.
If the user adds a "ftrace=" to the kernel command line, then the ring
buffers will be set to the default size on initialization.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: prevent locking up by lockdep tracer
The lockdep tracer uses trace_vprintk and thus trace_vprintk can not
call back into lockdep without locking up.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Using the function_graph tracer in recent kernels generates a spew of
preemption BUGs. Fix this by not requiring trace_clock_local() users
to disable preemption themselves.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
There existed a lot of <space><tab>'s in the tracing code. This
patch removes them.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up / comments
The comments that described the ftrace macros to manipulate the
TRACE_EVENT and TRACE_FORMAT macros no longer match the code.
This patch updates them.
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
In trying to stay consistant with the C style format in the TRACE_EVENT
macro, it makes more sense to do the printk after the assigning of
the variables.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The event directory files type and available_types were no longer
needed with the new TRACE_EVENT_FORMAT macros, they were deleted.
But by accident the available_events file was also removed.
This patch brings it back.
Reported-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to prevent crash on calling NULL function pointer
The ftrace internal records have their format exported via the event
system under the ftrace subsystem. These are only for exporting the
format to allow binary readers to be able to parse them in a binary
output.
The ftrace subsystem events can only be enabled via the ftrace tracers
and do not have a registering function. The event files expect the
event record to have registering function and will call it directly.
Passing in a ftrace subsystem event will cause the kernel to crash
because it will execute a NULL pointer.
This patch prevents the ftrace subsystem from being viewable to the
event enabling files.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The offsetof and sizeof are of type size_t, and instead of typecasting
them to unsigned int for printk formatting, one could just use %zu.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
"for (++cpu ; cpu < num_possible_cpus(); cpu++)" statement assumes
possible cpus have continuous number - but that's a wrong assumption.
Insted, cpumask_next() should be used.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20090310104437.A480.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: clean up
The TRACE_EVENT_FORMAT macro is no longer used by trace points
and only the DECLARE_TRACE, TRACE_FORMAT or TRACE_EVENT macros should
be used by them. Although the TRACE_EVENT_FORMAT macro is still used
by the internal tracing utility, it should not be used in core
kernel code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up and enhancement
The TRACE_EVENT_FORMAT macro looks quite ugly and is limited in its
ability to save data as well as to print the record out. Working with
Ingo Molnar, we came up with a new format that is much more pleasing to
the eye of C developers. This new macro is more C style than the old
macro, and is more obvious to what it does.
Here's the example. The only updated macro in this patch is the
sched_switch trace point.
The old method looked like this:
TRACE_EVENT_FORMAT(sched_switch,
TP_PROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TP_ARGS(rq, prev, next),
TP_FMT("task %s:%d ==> %s:%d",
prev->comm, prev->pid, next->comm, next->pid),
TRACE_STRUCT(
TRACE_FIELD(pid_t, prev_pid, prev->pid)
TRACE_FIELD(int, prev_prio, prev->prio)
TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
next_comm,
TP_CMD(memcpy(TRACE_ENTRY->next_comm,
next->comm,
TASK_COMM_LEN)))
TRACE_FIELD(pid_t, next_pid, next->pid)
TRACE_FIELD(int, next_prio, next->prio)
),
TP_RAW_FMT("prev %d:%d ==> next %s:%d:%d")
);
The above method is hard to read and requires two format fields.
The new method:
/*
* Tracepoint for task switches, performed by the scheduler:
*
* (NOTE: the 'rq' argument is not used by generic trace events,
* but used by the latency tracer plugin. )
*/
TRACE_EVENT(sched_switch,
TP_PROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TP_ARGS(rq, prev, next),
TP_STRUCT__entry(
__array( char, prev_comm, TASK_COMM_LEN )
__field( pid_t, prev_pid )
__field( int, prev_prio )
__array( char, next_comm, TASK_COMM_LEN )
__field( pid_t, next_pid )
__field( int, next_prio )
),
TP_printk("task %s:%d [%d] ==> %s:%d [%d]",
__entry->prev_comm, __entry->prev_pid, __entry->prev_prio,
__entry->next_comm, __entry->next_pid, __entry->next_prio),
TP_fast_assign(
memcpy(__entry->next_comm, next->comm, TASK_COMM_LEN);
__entry->prev_pid = prev->pid;
__entry->prev_prio = prev->prio;
memcpy(__entry->prev_comm, prev->comm, TASK_COMM_LEN);
__entry->next_pid = next->pid;
__entry->next_prio = next->prio;
)
);
This macro is called TRACE_EVENT, it is broken up into 5 parts:
TP_PROTO: the proto type of the trace point
TP_ARGS: the arguments of the trace point
TP_STRUCT_entry: the structure layout of the entry in the ring buffer
TP_printk: the printk format
TP_fast_assign: the method used to write the entry into the ring buffer
The structure is the definition of how the event will be saved in the
ring buffer. The printk is used by the internal tracing in case of
an oops, and the kernel needs to print out the format of the record
to the console. This the TP_printk gives a means to show the records
in a human readable format. It is also used to print out the data
from the trace file.
The TP_fast_assign is executed directly. It is basically like a C function,
where the __entry is the handle to the record.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
This removes the custom made STR(x) macros in the tracer and uses
the generic __stringify macro instead.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The macros TPPROTO, TPARGS, TPFMT, TPRAWFMT, and TPCMD all look a bit
ugly. This patch adds an underscore to their names.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix compiler warnings
On x86_64 sizeof and offsetof are treated as long, where as on x86_32
they are int. This patch typecasts them to unsigned int to avoid
one arch giving warnings while the other does not.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: improve workqueue tracer output
Currently, /sys/kernel/debug/tracing/trace_stat/workqueues can display
wrong and strange thread names.
Why?
Currently, ftrace has tracing_record_cmdline()/trace_find_cmdline()
convenience function that implements a task->comm string cache.
This can avoid unnecessary memcpy overhead and the workqueue tracer
uses it.
However, in general, any trace statistics feature shouldn't use
tracing_record_cmdline() because trace statistics can display
very old process. Then comm cache can return wrong string because
recent process overrides the cache.
Fortunately, workqueue trace guarantees that displayed processes
are live. Thus we can search comm string from PID at display time.
<before>
% cat workqueues
# CPU INSERTED EXECUTED NAME
# | | | |
7 431913 431913 kondemand/7
7 0 0 tail
7 21 21 git
7 0 0 ls
7 9 9 cat
7 832632 832632 unix_chkpwd
7 236292 236292 ls
Note: tail, git, ls, cat unix_chkpwd are obiously not workqueue thread.
<after>
% cat workqueues
# CPU INSERTED EXECUTED NAME
# | | | |
7 510 510 kondemand/7
7 0 0 kmpathd/7
7 15 15 ata/7
7 0 0 aio/7
7 11 11 kblockd/7
7 1063 1063 work_on_cpu/7
7 167 167 events/7
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Remove a few leftovers and clean up the code a bit.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: faster and lighter tracing
Now that we have trace_bprintk() which is faster and consume lesser
memory than trace_printk() and has the same purpose, we can now drop
the old implementation in favour of the binary one from trace_bprintk(),
which means we move all the implementation of trace_bprintk() to
trace_printk(), so the Api doesn't change except that we must now use
trace_seq_bprintk() to print the TRACE_PRINT entries.
Some changes result of this:
- Previously, trace_bprintk depended of a single tracer and couldn't
work without. This tracer has been dropped and the whole implementation
of trace_printk() (like the module formats management) is now integrated
in the tracing core (comes with CONFIG_TRACING), though we keep the file
trace_printk (previously trace_bprintk.c) where we can find the module
management. Thus we don't overflow trace.c
- changes some parts to use trace_seq_bprintk() to print TRACE_PRINT entries.
- change a bit trace_printk/trace_vprintk macros to support non-builtin formats
constants, and fix 'const' qualifiers warnings. But this is all transparent for
developers.
- etc...
V2:
- Rebase against last changes
- Fix mispell on the changelog
V3:
- Rebase against last changes (moving trace_printk() to kernel.h)
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-5-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: add a generic printk() for tracing, like trace_printk()
trace_bprintk() uses the infrastructure to record events on ring_buffer.
[ fweisbec@gmail.com: ported to latest -tip, made it work if
!CONFIG_MODULES, never free the format strings from modules
because we can't keep track of them and conditionnaly create
the ftrace format strings section (reported by Steven Rostedt) ]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-4-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: save on memory for tracing
Current tracers are typically using a struct(like struct ftrace_entry,
struct ctx_switch_entry, struct special_entr etc...)to record a binary
event. These structs can only record a their own kind of events.
A new kind of tracer need a new struct and a lot of code too handle it.
So we need a generic binary record for events. This infrastructure
is for this purpose.
[fweisbec@gmail.com: rebase against latest -tip, make it safe while sched
tracing as reported by Steven Rostedt]
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1236356510-8381-3-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: fix deadlock while using set_ftrace_pid
Reproducer:
# cd /sys/kernel/debug/tracing
# echo $$ > set_ftrace_pid
then, console becomes hung.
Details:
when writing set_ftracepid, kernel callstack is following
ftrace_pid_write()
mutex_lock(&ftrace_lock);
ftrace_update_pid_func()
mutex_lock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
mutex_unlock(&ftrace_lock);
then, system always deadlocks when ftrace_pid_write() is called.
In past days, ftrace_pid_write() used ftrace_start_lock, but
commit e6ea44e9b4 consolidated
ftrace_start_lock to ftrace_lock.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Steven Rostedt <srostedt@redhat.com>
LKML-Reference: <20090306151155.0778.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: allow user apps to read binary format of basic ftrace entries
Currently, only defined raw events export their formats so a binary
reader can parse them. There's no reason that the default ftrace entries
can't export their formats.
This patch adds a subsystem called "ftrace" in the events directory
that includes the ftrace entries for basic ftrace recorded items.
These only have three files in the events directory:
type : printf
available_types : printf
format : format for the event entry
For example:
# cat /debug/tracing/events/ftrace/wakeup/format
name: wakeup
ID: 3
format:
field:unsigned char type; offset:0; size:1;
field:unsigned char flags; offset:1; size:1;
field:unsigned char preempt_count; offset:2; size:1;
field:int pid; offset:4; size:4;
field:int tgid; offset:8; size:4;
field:unsigned int prev_pid; offset:12; size:4;
field:unsigned char prev_prio; offset:16; size:1;
field:unsigned char prev_state; offset:17; size:1;
field:unsigned int next_pid; offset:20; size:4;
field:unsigned char next_prio; offset:24; size:1;
field:unsigned char next_state; offset:25; size:1;
field:unsigned int next_cpu; offset:28; size:4;
print fmt: "%u:%u:%u ==+ %u:%u:%u [%03u]"
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
Move the macro that creates the event format file to a separate header.
This will allow the default ftrace events to use this same macro
to create the formats to read those events.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: cleanup
All file_operations structures should be constant. No one is going to
change them.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Clean up menu structure, introduce TRACING_SUPPORT switch that signals
whether an architecture supports various instrumentation mechanisms.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: decrease hangs risks with the graph tracer on slow systems
Since the function graph tracer can spend too much time on timer
interrupts, it's better now to use the more lightweight local
clock. Anyway, the function graph traces are more reliable on a
per cpu trace.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <49af243d.06e9300a.53ad.ffff840c@mx.google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Impact: cleanup
Use a more generic name - this also allows the prototype to move
to kernel.h and be generally available to kernel developers who
want to do some quick tracing.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The latency tracers (irqsoff, preemptoff, preemptirqsoff, and wakeup)
are pretty useless with the default output format. This patch makes them
automatically enable the latency format when they are selected. They
also record the state of the latency option, and if it was not enabled
when selected, they disable it on reset.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
Both print_lat_fmt and print_trace_fmt do pretty much the same thing
except for one different function call. This patch consolidates the
two functions and adds an if statement to perform the difference.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The trace and latency_trace function pointers are identical for
every tracer but the function tracer. The differences in the function
tracer are trivial (latency output puts paranthesis around parent).
This patch removes the latency_trace pointer and all prints will
now just use the trace output function pointer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
With the removal of the latency_trace file, we lost the ability
to see some of the finer details in a trace. Like the state of
interrupts enabled, the preempt count, need resched, and if we
are in an interrupt handler, softirq handler or not.
This patch simply creates an option to bring back the old format.
This also removes the warning about an unused variable that held
the latency_trace file operations.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The buffer used by trace_seq was updated incorrectly. Instead
of consuming what was actually read, it consumed the rest of the
buffer on reads.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix trace read to conform to standards
Andrew Morton, Theodore Tso and H. Peter Anvin brought to my attention
that a userspace read should not return -EFAULT if it succeeded in
copying anything. It should only return -EFAULT if it failed to copy
at all.
This patch modifies the check of copy_from_user and updates the return
code appropriately.
I also used H. Peter Anvin's short cut rule to just test ret == count.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
If a partial ring_buffer_page_read happens, then some of the
incremental timestamps may be lost. This patch writes the
recent timestamp into the page that is passed back to the caller.
A partial ring_buffer_page_read is where the full page would not
be written back to the user, and instead, just part of the page
is copied to the user. A full page would be a page swap with the
ring buffer and the timestamps would be correct.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to ftrace_dump output corruption
The commit: b04cc6b1f6
tracing/core: introduce per cpu tracing files
added a new field to the iterator called cpu_file. This was a handle
to differentiate between the per cpu trace output files and the
all cpu "trace" file. The all cpu "trace" file required setting this
to TRACE_PIPE_ALL_CPU.
The problem is that the ftrace_dump sets up its own iterator but was
not updated to handle this change. The result was only CPU 0 printing
out on crash and a lot of "<0>"'s also being printed.
Reported-by: Thomas Gleixner <tglx@linuxtronix.de>
Tested-by: Darren Hart <dvhtc@us.ibm.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: new feature
This patch creates a directory of files that correspond to the
per CPU ring buffers. These are binary files and are made to
be used with splice. This is the fastest way to extract data from
the ftrace ring buffers.
Thanks to Jiaying Zhang for pushing me to get this code fixed,
and to Eduard - Gabriel Munteanu for his splice code that helped
me debug my code.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: dont leave holes in read buffer page
The ring_buffer_read_page swaps a given page with the reader page
of the ring buffer, if certain conditions are set:
1) requested length is big enough to hold entire page data
2) a writer is not currently on the page
3) the page is not partially consumed.
Instead of swapping with the supplied page. It copies the data to
the supplied page instead. But currently the data is copied in the
same offset as the source page. This causes a hole at the start
of the reader page. This complicates the use of this function.
Instead, it should copy the data at the beginning of the function
and update the index fields accordingly.
Other small clean ups are also done in this patch.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix to possible alignment problems on some archs.
Some arch compilers include an NULL char array in the sizeof field.
Since the ring_buffer_event type includes one of these, it is better
to use the "offsetof" instead, to avoid strange bugs on these archs.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The ring_buffer_read_page was broken if it were to only copy part
of the page. This patch fixes that up as well as adds a parameter
to allow a length field, in order to only copy part of the buffer page.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: fix ring_buffer_read_page
After a page is swapped into the ring buffer, the write field must
also be reset.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The registering of events had the return value check backwards.
A zero returned is success, the check had it as a failure.
This patch also fixes a missing "\n" in the warning that the check
failed.
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
To be able to identify the trace in the binary format output, the
id of the trace event (which is dynamically assigned) must also be listed.
This patch adds the name of the trace point as well as the id assigned.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch includes the ftrace header to the event formats files:
# cat /debug/tracing/events/sched/sched_switch/format
field:unsigned char type; offset:0; size:1;
field:unsigned char flags; offset:1; size:1;
field:unsigned char preempt_count; offset:2; size:1;
field:int pid; offset:4; size:4;
field:int tgid; offset:8; size:4;
field:pid_t prev_pid; offset:12; size:4;
field:int prev_prio; offset:16; size:4;
field special:char next_comm[TASK_COMM_LEN]; offset:20; size:16;
field:pid_t next_pid; offset:36; size:4;
field:int next_prio; offset:40; size:4;
A blank line is used as a deliminator between the ftrace header and the
trace point fields.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch adds the "format" file to the trace point event directory.
This is based off of work by Tom Zanussi, in which a file is exported
to be tread from user land such that a user space app may read the
binary record stored in the ring buffer.
# cat /debug/tracing/events/sched/sched_switch/format
field:pid_t prev_pid; offset:12; size:4;
field:int prev_prio; offset:16; size:4;
field special:char next_comm[TASK_COMM_LEN]; offset:20; size:16;
field:pid_t next_pid; offset:36; size:4;
field:int next_prio; offset:40; size:4;
Idea-from: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: clean up
The trace_seq functions may be used separately outside of the ftrace
iterator. The trace_seq_reset is needed for these operations.
This patch also renames trace_seq_reset to the more appropriate
trace_seq_init.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
The trace event objects are currently not proctected against
reentrancy. This patch adds a mutex around the modifications of
the trace event fields.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Tom Zanussi pointed out that the simple TRACE_FIELD was not enough to
record trace data that required memcpy. This patch addresses this issue
by adding a TRACE_FIELD_SPECIAL. The format is similar to TRACE_FIELD
but looks like so:
TRACE_FIELD_SPECIAL(type_item, item, cmd)
What TRACE_FIELD gave was:
TRACE_FIELD(type, item, assign)
The TRACE_FIELD would be used in declaring a structure:
struct {
type item;
};
And later assign it via:
entry->item = assign;
What TRACE_FIELD_SPECIAL gives us is:
In the declaration of the structure:
struct {
type_item;
};
And the assignment:
cmd;
This change log will explain the one example used in the patch:
TRACE_EVENT_FORMAT(sched_switch,
TPPROTO(struct rq *rq, struct task_struct *prev,
struct task_struct *next),
TPARGS(rq, prev, next),
TPFMT("task %s:%d ==> %s:%d",
prev->comm, prev->pid, next->comm, next->pid),
TRACE_STRUCT(
TRACE_FIELD(pid_t, prev_pid, prev->pid)
TRACE_FIELD(int, prev_prio, prev->prio)
TRACE_FIELD_SPECIAL(char next_comm[TASK_COMM_LEN],
next_comm,
TPCMD(memcpy(TRACE_ENTRY->next_comm,
next->comm,
TASK_COMM_LEN)))
TRACE_FIELD(pid_t, next_pid, next->pid)
TRACE_FIELD(int, next_prio, next->prio)
),
TPRAWFMT("prev %d:%d ==> next %s:%d:%d")
);
The struct will be create as:
struct {
pid_t prev_pid;
int prev_prio;
char next_comm[TASK_COMM_LEN];
pid_t next_pid;
int next_prio;
};
Note the TRACE_ENTRY in the cmd part of TRACE_SPECIAL. TRACE_ENTRY will
be set by the tracer to point to the structure inside the trace buffer.
entry->prev_pid = prev->pid;
entry->prev_prio = prev->prio;
memcpy(entry->next_comm, next->comm, TASK_COMM_LEN);
entry->next_pid = next->pid;
entry->next_prio = next->prio
Reported-by: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
This patch adds the interface to enable the C style trace points.
In the directory /debugfs/tracing/events/subsystem/event
We now have three files:
enable : values 0 or 1 to enable or disable the trace event.
available_types: values 'raw' and 'printf' which indicate the tracing
types available for the trace point. If a developer does not
use the TRACE_EVENT_FORMAT macro and just uses the TRACE_FORMAT
macro, then only 'printf' will be available. This file is
read only.
type: values 'raw' or 'printf'. This indicates which type of tracing
is active for that trace point. 'printf' is the default and
if 'raw' is not available, this file is read only.
# echo raw > /debug/tracing/events/sched/sched_wakeup/type
# echo 1 > /debug/tracing/events/sched/sched_wakeup/enable
Will enable the C style tracing for the sched_wakeup trace point.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Impact: lower overhead tracing
The current event tracer can automatically pick up trace points
that are registered with the TRACE_FORMAT macro. But it required
a printf format string and parsing. Although, this adds the ability
to get guaranteed information like task names and such, it took
a hit in overhead processing. This processing can add about 500-1000
nanoseconds overhead, but in some cases that too is considered
too much and we want to shave off as much from this overhead as
possible.
Tom Zanussi recently posted tracing patches to lkml that are based
on a nice idea about capturing the data via C structs using
STRUCT_ENTER, STRUCT_EXIT type of macros.
I liked that method very much, but did not like the implementation
that required a developer to add data/code in several disjoint
locations.
This patch extends the event_tracer macros to do a similar "raw C"
approach that Tom Zanussi did. But instead of having the developers
needing to tweak a bunch of code all over the place, they can do it
all in one macro - preferably placed near the code that it is
tracing. That makes it much more likely that tracepoints will be
maintained on an ongoing basis by the code they modify.
The new macro TRACE_EVENT_FORMAT is created for this approach. (Note,
a developer may still utilize the more low level DECLARE_TRACE macros
if they don't care about getting their traces automatically in the event
tracer.)
They can also use the existing TRACE_FORMAT if they don't need to code
the tracepoint in C, but just want to use the convenience of printf.
So if the developer wants to "hardwire" a tracepoint in the fastest
possible way, and wants to acquire their data via a user space utility
in a raw binary format, or wants to see it in the trace output but not
sacrifice any performance, then they can implement the faster but
more complex TRACE_EVENT_FORMAT macro.
Here's what usage looks like:
TRACE_EVENT_FORMAT(name,
TPPROTO(proto),
TPARGS(args),
TPFMT(fmt, fmt_args),
TRACE_STUCT(
TRACE_FIELD(type1, item1, assign1)
TRACE_FIELD(type2, item2, assign2)
[...]
),
TPRAWFMT(raw_fmt)
);
Note name, proto, args, and fmt, are all identical to what TRACE_FORMAT
uses.
name: is the unique identifier of the trace point
proto: The proto type that the trace point uses
args: the args in the proto type
fmt: printf format to use with the event printf tracer
fmt_args: the printf argments to match fmt
TRACE_STRUCT starts the ability to create a structure.
Each item in the structure is defined with a TRACE_FIELD
TRACE_FIELD(type, item, assign)
type: the C type of item.
item: the name of the item in the stucture
assign: what to assign the item in the trace point callback
raw_fmt is a way to pretty print the struct. It must match
the order of the items are added in TRACE_STUCT
An example of this would be:
TRACE_EVENT_FORMAT(sched_wakeup,
TPPROTO(struct rq *rq, struct task_struct *p, int success),
TPARGS(rq, p, success),
TPFMT("task %s:%d %s",
p->comm, p->pid, success?"succeeded":"failed"),
TRACE_STRUCT(
TRACE_FIELD(pid_t, pid, p->pid)
TRACE_FIELD(int, success, success)
),
TPRAWFMT("task %d success=%d")
);
This creates us a unique struct of:
struct {
pid_t pid;
int success;
};
And the way the call back would assign these values would be:
entry->pid = p->pid;
entry->success = success;
The nice part about this is that the creation of the assignent is done
via macro magic in the event tracer. Once the TRACE_EVENT_FORMAT is
created, the developer will then have a faster method to record
into the ring buffer. They do not need to worry about the tracer itself.
The developer would only need to touch the files in include/trace/*.h
Again, I would like to give special thanks to Tom Zanussi for this
nice idea.
Idea-from: Tom Zanussi <tzanussi@gmail.com>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Right now all tracers must manage their own trace buffers. This was
to enforce tracers to be independent in case we finally decide to
allow each tracer to have their own trace buffer.
But now we are adding event tracing that writes to the current tracer's
buffer. This adds an interface to allow events to write to the current
tracer buffer without having to manage its own. Since event tracing
has no "tracer", and is just a way to hook into any other tracer.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
