Commit Graph

32 Commits

Author SHA1 Message Date
Li Zefan
44e9c8b7ad tracing/filters: return proper error code when writing filter file
- 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>
2009-04-12 11:59:29 +02:00
Li Zefan
8433a40eb7 tracing/filters: NIL-terminate user input filter
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>
2009-04-12 11:59:27 +02:00
Tom Zanussi
9a8118baae tracing: filter fix for TRACE_EVENT_FORMAT events
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>
2009-03-26 09:13:14 +01:00
Tom Zanussi
4bda2d517b tracing/filters: use trace_seq_printf() to print filters
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>
2009-03-24 08:26:52 +01:00
Tom Zanussi
09f1f245c7 tracing/filters: free pred when clearing filters
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>
2009-03-24 08:26:51 +01:00
Tom Zanussi
c4cff064be tracing/filters: clean up filter_add_subsystem_pred()
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>
2009-03-23 09:30:37 +01:00
Frederic Weisbecker
9bd7d099ab tracing/events: make the filter files writable
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>
2009-03-23 09:22:14 +01:00
Ingo Molnar
fe9f57f250 tracing: add run-time field descriptions for event filtering, kfree fix
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>
2009-03-22 18:43:25 +01:00
Tom Zanussi
cfb180f3e7 tracing: add per-subsystem filtering
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>
2009-03-22 18:38:47 +01:00
Tom Zanussi
7ce7e42499 tracing: add per-event filtering
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>
2009-03-22 18:38:46 +01:00
Tom Zanussi
cf027f645e tracing: add run-time field descriptions for event filtering
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>
2009-03-22 18:11:22 +01:00
Peter Zijlstra
ac199db018 ftrace: event profile hooks
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>
2009-03-20 10:17:07 +01:00
Peter Zijlstra
23725aeeab ftrace: provide an id file for each event
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>
2009-03-20 10:17:05 +01:00
Tom Zanussi
c269fc8c53 tracing: fix leak in event_format_read()
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>
2009-03-17 08:38:23 +01:00
Steven Rostedt
e9fb2b6d58 tracing: have event_trace_printk use static tracer
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>
2009-03-12 21:15:00 -04:00
Steven Rostedt
1852fcce18 tracing: expand the ring buffers when an event is activated
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>
2009-03-11 22:15:24 -04:00
Steven Rostedt
2314c4ae14 tracing: add back the available_events file
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>
2009-03-10 12:04:02 -04:00
Steven Rostedt
40e26815fa tracing: do not allow modifying the ftrace events via the event files
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>
2009-03-10 11:32:40 -04:00
Steven Rostedt
ce8eb2bf05 tracing: fix printk format specifier
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>
2009-03-10 10:14:35 -04:00
Steven Rostedt
da4d03020c tracing: new format for specialized trace points
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>
2009-03-10 00:35:07 -04:00
Steven Rostedt
156b5f172a tracing: typecast sizeof and offsetof to unsigned int
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>
2009-03-10 00:34:03 -04:00
Steven Rostedt
770cb24345 tracing: add format files for ftrace default entries
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>
2009-03-05 21:46:44 -05:00
Steven Rostedt
c5e4e19271 tracing: add trace name and id to event formats
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>
2009-03-02 15:10:02 -05:00
Steven Rostedt
91729ef966 tracing: add ftrace headers to event format files
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>
2009-03-02 15:03:01 -05:00
Steven Rostedt
981d081ec8 tracing: add format file to describe event struct fields
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>
2009-03-02 14:27:27 -05:00
Steven Rostedt
11a241a330 tracing: add protection around modify trace event fields
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>
2009-03-02 11:49:04 -05:00
Steven Rostedt
fd99498989 tracing: add raw fast tracing interface for trace events
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>
2009-02-28 04:04:03 -05:00
Steven Rostedt
c32e827b25 tracing: add raw trace point recording infrastructure
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>
2009-02-28 03:09:32 -05:00
Steven Rostedt
b628b3e629 tracing: make the set_event and available_events subsystem aware
This patch makes the event files, set_event and available_events
aware of the subsystem.

Now you can enable an entire subsystem with:

  echo 'irq:*' > set_event

Note: the '*' is not needed.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-28 03:05:40 -05:00
Steven Rostedt
6ecc2d1ca3 tracing: add subsystem level to trace events
If a trace point header defines TRACE_SYSTEM, then it will add the
following trace points into that event system.

If include/trace/irq_event_types.h has:

 #define TRACE_SYSTEM irq

at the top and

 #undef TRACE_SYSTEM

at the bottom, then a directory "irq" will be created in the
/debug/tracing/events directory. Inside that directory will contain the
two trace points that are defined in include/trace/irq_event_types.h.

Only adding the above to irq and not to sched, we get:

 # ls /debug/tracing/events/
irq                     sched_process_exit  sched_signal_send  sched_wakeup_new
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup

 # ls /debug/tracing/events/irq
irq_handler_entry  irq_handler_exit

If we add #define TRACE_SYSTEM sched to the trace/sched_event_types.h
then the rest of the trace events will be put in a sched directory
within the events directory.

I've been playing with this idea of the subsystem for a while, but
recently Tom Zanussi posted some patches to lkml that included this
method. Tom's approach was clean and got me to finally put some effort
to clean up the event trace points.

Thanks to Tom Zanussi for demonstrating how nice the subsystem
method is.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-28 02:59:43 -05:00
Steven Rostedt
1473e4417c tracing: make event directory structure
This patch adds the directory /debug/tracing/events/ that will contain
all the registered trace points.

 # ls /debug/tracing/events/
sched_kthread_stop      sched_process_fork  sched_switch
sched_kthread_stop_ret  sched_process_free  sched_wait_task
sched_migrate_task      sched_process_wait  sched_wakeup
sched_process_exit      sched_signal_send   sched_wakeup_new

 # ls /debug/tracing/events/sched_switch/
enable

 # cat /debug/tracing/events/sched_switch/enable
1

 # cat /debug/tracing/set_event
sched_switch

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-24 21:54:08 -05:00
Steven Rostedt
b77e38aa24 tracing: add event trace infrastructure
This patch creates the event tracing infrastructure of ftrace.
It will create the files:

 /debug/tracing/available_events
 /debug/tracing/set_event

The available_events will list the trace points that have been
registered with the event tracer.

set_events will allow the user to enable or disable an event hook.

example:

 # echo sched_wakeup > /debug/tracing/set_event

Will enable the sched_wakeup event (if it is registered).

 # echo "!sched_wakeup" >> /debug/tracing/set_event

Will disable the sched_wakeup event (and only that event).

 # echo > /debug/tracing/set_event

Will disable all events (notice the '>')

 # cat /debug/tracing/available_events > /debug/tracing/set_event

Will enable all registered event hooks.

Signed-off-by: Steven Rostedt <srostedt@redhat.com>
2009-02-24 21:54:05 -05:00