linux-kernel - Re: [Resend][PATCH] PM / tick: Add tracepoints for suspend-to-idle diagnostics

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Date:	Fri, 15 May 2015 00:04:57 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>
Subject: Re: [Resend][PATCH] PM / tick: Add tracepoints for suspend-to-idle diagnostics

On Sunday, May 10, 2015 01:23:35 AM Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> 
> Add suspend/resume tracepoints to tick_freeze() and tick_unfreeze()
> to catch when timekeeping is suspended and resumed during suspend-to-idle
> so as to be able to check whether or not we enter the "frozen" state
> and to measure the time spent in it.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Thomas, Peter, any objections here?

> ---
> 
> Sorry for the duplication, but I messed up the Thomas' address in the previous one.
> 
> ---
>  kernel/time/tick-common.c |   15 +++++++++++----
>  1 file changed, 11 insertions(+), 4 deletions(-)
> 
> Index: linux-pm/kernel/time/tick-common.c
> ===================================================================
> --- linux-pm.orig/kernel/time/tick-common.c
> +++ linux-pm/kernel/time/tick-common.c
> @@ -19,6 +19,7 @@
>  #include <linux/profile.h>
>  #include <linux/sched.h>
>  #include <linux/module.h>
> +#include <trace/events/power.h>
>  
>  #include <asm/irq_regs.h>
>  
> @@ -457,10 +458,13 @@ void tick_freeze(void)
>  	raw_spin_lock(&tick_freeze_lock);
>  
>  	tick_freeze_depth++;
> -	if (tick_freeze_depth == num_online_cpus())
> +	if (tick_freeze_depth == num_online_cpus()) {
> +		trace_suspend_resume(TPS("timekeeping_freeze"),
> +				     smp_processor_id(), true);
>  		timekeeping_suspend();
> -	else
> +	} else {
>  		tick_suspend_local();
> +	}
>  
>  	raw_spin_unlock(&tick_freeze_lock);
>  }
> @@ -478,10 +482,13 @@ void tick_unfreeze(void)
>  {
>  	raw_spin_lock(&tick_freeze_lock);
>  
> -	if (tick_freeze_depth == num_online_cpus())
> +	if (tick_freeze_depth == num_online_cpus()) {
>  		timekeeping_resume();
> -	else
> +		trace_suspend_resume(TPS("timekeeping_freeze"),
> +				     smp_processor_id(), false);
> +	} else {
>  		tick_resume_local();
> +	}
>  
>  	tick_freeze_depth--;
>  
> 
> --
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-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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