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

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Date:	Wed, 20 May 2009 12:31:36 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Anton Blanchard <anton@...ba.org>
cc:	rostedt@...dmis.org, mingo@...e.hu, tzanussi@...il.com,
	jbaron@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] tracing/events: Add timer and high res timer
 tracepoints

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@...ba.org>

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