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Message-ID: <alpine.LFD.2.00.0907062140010.19480@localhost.localdomain>
Date: Mon, 6 Jul 2009 22:08:52 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
cc: Ingo Molnar <mingo@...e.hu>, Steven Rostedt <rostedt@...dmis.org>,
Frederic Weisbecker <fweisbec@...il.com>,
Mathieu Desnoyers <mathieu.desnoyers@...ymtl.ca>,
Zhaolei <zhaolei@...fujitsu.com>, kosaki.motohiro@...fujitsu.com,
LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] ftrace: add tracepoint for timer
On Mon, 6 Jul 2009, Xiao Guangrong wrote:
> Changelog v1->v2:
> 1: Add jiffies info into timer
> 2: Combine debugobjects and trace as Thomas's suggestion
I like it that way. Some minor nitpicks below.
> +TRACE_EVENT(timer_expire,
> +
> + TP_PROTO(struct timer_list *timer),
> +
> + TP_ARGS(timer),
> +
> + TP_STRUCT__entry(
> + __field( void *, timer )
> + __field( void *, function )
Do we really need the function here? It does not change between
start and expiry.
> +TRACE_EVENT(timer_cancel,
> +
> + TP_PROTO(struct timer_list *timer),
> +
> + TP_ARGS(timer),
> +
> + TP_STRUCT__entry(
> + __field( void *, timer )
> + __field( void *, function )
Ditto.
> +
> +static inline void debug_and_trace_timer_expire(struct timer_list *timer)
Technically not really necessary. The debug code does not care about
it.
> timer = list_first_entry(head, struct timer_list,entry);
> + debug_and_trace_timer_expire(timer);
> fn = timer->function;
> data = timer->data;
>
Can you please add the tracepoint which was suggested by Anton (IIRC)
which allows us to measure the execution time of the callback function
? There is no need to dereference timer in the expiry tracepoint, we
just store the pointer. So we can safely move the tracepoints just
around the function call.
trace_timer_expire(timer);
fn(data);
trace_timer_callback_done(timer);
Or whatever fancy name you come up with.
Thanks,
tglx
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