Re: [PATCH] tracing/events: Add timer and high res timer tracepoints

Thomas Gleixner
2009-05-20T10:32:43Z

On Wed, 20 May 2009, Anton Blanchard wrote:
>
> Add tracepoints for timer and high res timer execution. We add entry and
> exit tracepoints so we can calculate timer latency.
>
> Example ftrace output:
>
> <idle>-0 [000] 264.040506: hrtimer_entry: func=.tick_sched_timer+0x0/0xf0
> <idle>-0 [000] 264.040508: hrtimer_exit: func=.tick_sched_timer+0x0/0xf0 restart=HRTIMER_RESTART
> <idle>-0 [000] 264.040530: timer_entry: func=.e1000_watchdog+0x0/0x8fc
> <idle>-0 [000] 264.040728: timer_exit: func=.e1000_watchdog+0x0/0x8fc
>
> Here we can see e1000_watchdog is taking 0.2ms - it might make sense to
> move this into a workqueue or kernel thread.

Cute. That should help us to pinpoint more such timer abusers :)

> Signed-off-by: Anton Blanchard <anton@samba.org>

Acked-by: Thomas Gleixner <tglx@linutronix.de>