35e8e302e5
This patch adds context switch tracing, of the format of:
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | pid:prio:state
\ / ||||| \ | /
swapper-0 1d..3 137us+: 0:140:R --> 2912:120
sshd-2912 1d..3 216us+: 2912:120:S --> 0:140
swapper-0 1d..3 261us+: 0:140:R --> 2912:120
bash-2920 0d..3 267us+: 2920:120:S --> 0:140
sshd-2912 1d..3 330us!: 2912:120:S --> 0:140
swapper-0 1d..3 2389us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 2411us!: 2847:120:S --> 0:140
swapper-0 0d..3 11089us+: 0:140:R --> 3139:120
gdm-bina-3139 0d..3 11113us!: 3139:120:S --> 0:140
swapper-0 1d..3 102328us+: 0:140:R --> 2847:120
yum-upda-2847 1d..3 102348us!: 2847:120:S --> 0:140
"sched_switch" is added to /debugfs/tracing/available_tracers
[ Eugene Teo <eugeneteo@kernel.sg: remove unused tracing_sched_switch_enabled ]
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
35 lines
992 B
Plaintext
35 lines
992 B
Plaintext
#
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# Architectures that offer an FTRACE implementation should select HAVE_FTRACE:
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#
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config HAVE_FTRACE
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bool
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config TRACING
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bool
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select DEBUG_FS
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config FTRACE
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bool "Kernel Function Tracer"
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depends on DEBUG_KERNEL && HAVE_FTRACE
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select FRAME_POINTER
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select TRACING
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select CONTEXT_SWITCH_TRACER
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help
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Enable the kernel to trace every kernel function. This is done
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by using a compiler feature to insert a small, 5-byte No-Operation
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instruction to the beginning of every kernel function, which NOP
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sequence is then dynamically patched into a tracer call when
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tracing is enabled by the administrator. If it's runtime disabled
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(the bootup default), then the overhead of the instructions is very
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small and not measurable even in micro-benchmarks.
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config CONTEXT_SWITCH_TRACER
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bool "Trace process context switches"
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depends on DEBUG_KERNEL
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select TRACING
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select MARKERS
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help
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This tracer gets called from the context switch and records
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all switching of tasks.
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