linux-kernel - Re: [PATCH v2] arm: add cpu_idle tracepoints to arch_cpu

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Date:	Thu, 17 Sep 2015 16:07:44 +0800
From:	Jisheng Zhang <jszhang@...vell.com>
To:	<linux@....linux.org.uk>, <rostedt@...dmis.org>,
	<mingo@...hat.com>, <trenn@...e.de>, <arjan@...ux.intel.com>
CC:	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] arm: add cpu_idle tracepoints to arch_cpu_idle

Dear all,

On Thu, 17 Sep 2015 01:32:40 +0800
Jisheng Zhang <jszhang@...vell.com> wrote:

> Currently, if cpuidle is disabled or not supported, powertop reports
> zero wakeups and zero events. This is due to the cpu_idle tracepoints
> are missing.
> 
> This patch is to make cpu_idle tracepoints always available even if
> cpuidle is disabled or not supported.
> 
> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
> ---
>  Since v1:
>    - ignore arm_pm_idle.

Something related: let's have a look at arch/arm/mach-omap2/pm34xx.c
the omap3_pm_idle(void) function, it uses trace_cpu_idle(), should we
use the _rcuidle version as below:

diff --git a/arch/arm/mach-omap2/pm34xx.c b/arch/arm/mach-omap2/pm34xx.c
index 87b98bf9..b3bc972 100644
--- a/arch/arm/mach-omap2/pm34xx.c
+++ b/arch/arm/mach-omap2/pm34xx.c
@@ -301,11 +301,11 @@ static void omap3_pm_idle(void)
 	if (omap_irq_pending())
 		return;
 
-	trace_cpu_idle(1, smp_processor_id());
+	trace_cpu_rcuidle(1, smp_processor_id());
 
 	omap_sram_idle();
 
-	trace_cpu_idle(PWR_EVENT_EXIT, smp_processor_id());
+	trace_cpu_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
 }
 
 #ifdef CONFIG_SUSPEND



>  arch/arm/kernel/process.c | 11 ++++++++---
>  1 file changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/arm/kernel/process.c b/arch/arm/kernel/process.c
> index 7a7c4ce..83d2dc5 100644
> --- a/arch/arm/kernel/process.c
> +++ b/arch/arm/kernel/process.c
> @@ -28,6 +28,7 @@
>  #include <linux/random.h>
>  #include <linux/hw_breakpoint.h>
>  #include <linux/leds.h>
> +#include <trace/events/power.h>
>  
>  #include <asm/processor.h>
>  #include <asm/thread_notify.h>
> @@ -66,11 +67,15 @@ void (*arm_pm_idle)(void);
>  
>  void arch_cpu_idle(void)
>  {
> -	if (arm_pm_idle)
> +	if (arm_pm_idle) {
>  		arm_pm_idle();
> -	else
> +		local_irq_enable();
> +	} else {
> +		trace_cpu_idle_rcuidle(1, smp_processor_id());
>  		cpu_do_idle();
> -	local_irq_enable();
> +		local_irq_enable();
> +		trace_cpu_idle_rcuidle(PWR_EVENT_EXIT, smp_processor_id());
> +	}
>  }
>  
>  void arch_cpu_idle_prepare(void)

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