linux-kernel - Re: [PATCH 4/6] trace: Add tracepoints to reschedule interrupt handler

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Date:	Fri, 15 Jul 2011 00:02:35 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Vaibhav Nagarnaik <vnagarnaik@...gle.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	Steven Rostedt <rostedt@...dmis.org>,
	Michael Rubin <mrubin@...gle.com>,
	David Sharp <dhsharp@...gle.com>, linux-kernel@...r.kernel.org,
	x86@...nel.org
Subject: Re: [PATCH 4/6] trace: Add tracepoints to reschedule interrupt
 handler

Looks good to me. But I'm adding Peter in Cc.

On Thu, Jul 14, 2011 at 02:38:13PM -0700, Vaibhav Nagarnaik wrote:
> This is a part of overall effort to trace all the interrupts happening
> in a system to figure out what time is spent in kernel space versus user
> space.
> 
> Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@...gle.com>
> ---
>  include/trace/events/irq.h |   45 ++++++++++++++++++++++++++++++++++++++++++++
>  kernel/sched.c             |    4 +++
>  2 files changed, 49 insertions(+), 0 deletions(-)
> 
> diff --git a/include/trace/events/irq.h b/include/trace/events/irq.h
> index d8fab89..a2a0a49 100644
> --- a/include/trace/events/irq.h
> +++ b/include/trace/events/irq.h
> @@ -339,6 +339,51 @@ DEFINE_EVENT(irq_work, irq_work_run_exit,
>  	TP_ARGS(ignore)
>  );
>  
> +DECLARE_EVENT_CLASS(reschedule_interrupt,
> +
> +	TP_PROTO(unsigned int ignore),
> +
> +	TP_ARGS(ignore),
> +
> +	TP_STRUCT__entry(
> +		__field(	unsigned int,	ignore	)
> +	),
> +
> +	TP_fast_assign(
> +		__entry->ignore = ignore;
> +	),
> +
> +	TP_printk("%u", __entry->ignore)
> +);
> +
> +/**
> + * reschedule_interrupt_entry - called immediately after entering the
> + * reschedule interrupt handler
> + *
> + * When used in combination with the reschedule_interrupt_exit tracepoint
> + * we can determine the reschedule interrupt handler runtime.
> + */
> +DEFINE_EVENT(reschedule_interrupt, reschedule_interrupt_entry,
> +
> +	TP_PROTO(unsigned int ignore),
> +
> +	TP_ARGS(ignore)
> +);
> +
> +/**
> + * reschedule_interrupt_exit - called just before the reschedule interrupt
> + * handler returns
> + *
> + * When used in combination with the reschedule_interrupt_entry tracepoint
> + * we can determine the reschedule interrupt handler runtime.
> + */
> +DEFINE_EVENT(reschedule_interrupt, reschedule_interrupt_exit,
> +
> +	TP_PROTO(unsigned int ignore),
> +
> +	TP_ARGS(ignore)
> +);
> +
>  #endif /*  _TRACE_IRQ_H */
>  
>  /* This part must be outside protection */
> diff --git a/kernel/sched.c b/kernel/sched.c
> index 9769c75..605c938 100644
> --- a/kernel/sched.c
> +++ b/kernel/sched.c
> @@ -79,6 +79,8 @@
>  #include "sched_cpupri.h"
>  #include "workqueue_sched.h"
>  #include "sched_autogroup.h"
> +#include <trace/events/irq.h>
> +
>  
>  #define CREATE_TRACE_POINTS
>  #include <trace/events/sched.h>
> @@ -2565,7 +2567,9 @@ static void sched_ttwu_pending(void)
>  
>  void scheduler_ipi(void)
>  {
> +	trace_reschedule_interrupt_entry(0);
>  	sched_ttwu_pending();
> +	trace_reschedule_interrupt_exit(0);
>  }
>  
>  static void ttwu_queue_remote(struct task_struct *p, int cpu)
> -- 
> 1.7.3.1
> 
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