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| author | Steven Rostedt <srostedt@redhat.com> | 2008-05-12 21:20:42 +0200 |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2008-05-23 20:32:36 +0200 |
| commit | 352ad25aa4a189c667cb2af333948d34692a2d27 (patch) | |
| tree | 83a11c626b3818711d3b88061964c9ea603f7b68 /kernel/trace/Kconfig | |
| parent | ftrace: add tracing of context switches (diff) | |
| download | linux-352ad25aa4a189c667cb2af333948d34692a2d27.tar.xz linux-352ad25aa4a189c667cb2af333948d34692a2d27.zip | |
ftrace: tracer for scheduler wakeup latency
This patch adds the tracer that tracks the wakeup latency of the
highest priority waking task.
"wakeup" is added to /debugfs/tracing/available_tracers
Also added to /debugfs/tracing
tracing_max_latency
holds the current max latency for the wakeup
wakeup_thresh
if set to other than zero, a log will be recorded
for every wakeup that takes longer than the number
entered in here (usecs for all counters)
(deletes previous trace)
Examples:
(with ftrace_enabled = 0)
============
preemption latency trace v1.1.5 on 2.6.24-rc8
Signed-off-by: Ingo Molnar <mingo@elte.hu>
--------------------------------------------------------------------
latency: 26 us, #2/2, CPU#1 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
-----------------
| task: migration/0-3 (uid:0 nice:-5 policy:1 rt_prio:99)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
quilt-8551 0d..3 0us+: wake_up_process+0x15/0x17 <ffffffff80233e80> (sched_exec+0xc9/0x100 <ffffffff80235343>)
quilt-8551 0d..4 26us : sched_switch_callback+0x73/0x81 <ffffffff80338d2f> (schedule+0x483/0x6d5 <ffffffff8048b3ee>)
vim:ft=help
============
(with ftrace_enabled = 1)
============
preemption latency trace v1.1.5 on 2.6.24-rc8
--------------------------------------------------------------------
latency: 36 us, #45/45, CPU#0 | (M:rt VP:0, KP:0, SP:0 HP:0 #P:2)
-----------------
| task: migration/1-5 (uid:0 nice:-5 policy:1 rt_prio:99)
-----------------
_------=> CPU#
/ _-----=> irqs-off
| / _----=> need-resched
|| / _---=> hardirq/softirq
||| / _--=> preempt-depth
|||| /
||||| delay
cmd pid ||||| time | caller
\ / ||||| \ | /
bash-10653 1d..3 0us : wake_up_process+0x15/0x17 <ffffffff80233e80> (sched_exec+0xc9/0x100 <ffffffff80235343>)
bash-10653 1d..3 1us : try_to_wake_up+0x271/0x2e7 <ffffffff80233dcf> (sub_preempt_count+0xc/0x7a <ffffffff8023309e>)
bash-10653 1d..2 2us : try_to_wake_up+0x296/0x2e7 <ffffffff80233df4> (update_rq_clock+0x9/0x20 <ffffffff802303f3>)
bash-10653 1d..2 2us : update_rq_clock+0x1e/0x20 <ffffffff80230408> (__update_rq_clock+0xc/0x90 <ffffffff80230366>)
bash-10653 1d..2 3us : __update_rq_clock+0x1b/0x90 <ffffffff80230375> (sched_clock+0x9/0x29 <ffffffff80214529>)
bash-10653 1d..2 4us : try_to_wake_up+0x2a6/0x2e7 <ffffffff80233e04> (activate_task+0xc/0x3f <ffffffff8022ffca>)
bash-10653 1d..2 4us : activate_task+0x2d/0x3f <ffffffff8022ffeb> (enqueue_task+0xe/0x66 <ffffffff8022ff66>)
bash-10653 1d..2 5us : enqueue_task+0x5b/0x66 <ffffffff8022ffb3> (enqueue_task_rt+0x9/0x3c <ffffffff80233351>)
bash-10653 1d..2 6us : try_to_wake_up+0x2ba/0x2e7 <ffffffff80233e18> (check_preempt_wakeup+0x12/0x99 <ffffffff80234f84>)
[...]
bash-10653 1d..5 33us : tracing_record_cmdline+0xcf/0xd4 <ffffffff80338aad> (_spin_unlock+0x9/0x33 <ffffffff8048d3ec>)
bash-10653 1d..5 34us : _spin_unlock+0x19/0x33 <ffffffff8048d3fc> (sub_preempt_count+0xc/0x7a <ffffffff8023309e>)
bash-10653 1d..4 35us : wakeup_sched_switch+0x65/0x2ff <ffffffff80339f66> (_spin_lock_irqsave+0xc/0xa9 <ffffffff8048d08b>)
bash-10653 1d..4 35us : _spin_lock_irqsave+0x19/0xa9 <ffffffff8048d098> (add_preempt_count+0xe/0x77 <ffffffff8023311a>)
bash-10653 1d..4 36us : sched_switch_callback+0x73/0x81 <ffffffff80338d2f> (schedule+0x483/0x6d5 <ffffffff8048b3ee>)
vim:ft=help
============
The [...] was added here to not waste your email box space.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Diffstat (limited to 'kernel/trace/Kconfig')
| -rw-r--r-- | kernel/trace/Kconfig | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 5d6aa92866cd..892ecc94a82b 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -4,6 +4,9 @@ config HAVE_FTRACE bool +config TRACER_MAX_TRACE + bool + config TRACING bool select DEBUG_FS @@ -23,6 +26,16 @@ config FTRACE (the bootup default), then the overhead of the instructions is very small and not measurable even in micro-benchmarks. +config SCHED_TRACER + bool "Scheduling Latency Tracer" + depends on DEBUG_KERNEL + select TRACING + select CONTEXT_SWITCH_TRACER + select TRACER_MAX_TRACE + help + This tracer tracks the latency of the highest priority task + to be scheduled in, starting from the point it has woken up. + config CONTEXT_SWITCH_TRACER bool "Trace process context switches" depends on DEBUG_KERNEL |