linux-kernel - Re: [PATCH 5/6] leds: Use all-in-one vtime aware kcpustat accessor

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Message-ID: <20191121164958.GA46146@gmail.com>
Date:   Thu, 21 Nov 2019 17:49:58 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Jacek Anaszewski <jacek.anaszewski@...il.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        "Rafael J . Wysocki" <rjw@...ysocki.net>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Rik van Riel <riel@...riel.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Yauheni Kaliuta <yauheni.kaliuta@...hat.com>,
        Viresh Kumar <viresh.kumar@...aro.org>,
        Pavel Machek <pavel@....cz>
Subject: Re: [PATCH 5/6] leds: Use all-in-one vtime aware kcpustat accessor


* Frederic Weisbecker <frederic@...nel.org> wrote:

> On Thu, Nov 21, 2019 at 07:58:26AM +0100, Ingo Molnar wrote:
> > 
> > * Frederic Weisbecker <frederic@...nel.org> wrote:
> > 
> > > We can now safely read user kcpustat fields on nohz_full CPUs.
> > > Use the appropriate accessor.
> > > 
> > > Reported-by: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
> > > Signed-off-by: Frederic Weisbecker <frederic@...nel.org>
> > > Cc: Jacek Anaszewski <jacek.anaszewski@...il.com>
> > > Cc: Pavel Machek <pavel@....cz>
> > > Cc: Yauheni Kaliuta <yauheni.kaliuta@...hat.com>
> > > Cc: Thomas Gleixner <tglx@...utronix.de>
> > > Cc: Rik van Riel <riel@...riel.com>
> > > Cc: Peter Zijlstra <peterz@...radead.org>
> > > Cc: Wanpeng Li <wanpengli@...cent.com>
> > > Cc: Ingo Molnar <mingo@...nel.org>
> > > ---
> > >  drivers/leds/trigger/ledtrig-activity.c | 14 +++++++++-----
> > >  1 file changed, 9 insertions(+), 5 deletions(-)
> > > 
> > > diff --git a/drivers/leds/trigger/ledtrig-activity.c b/drivers/leds/trigger/ledtrig-activity.c
> > > index ddfc5edd07c8..6901e3631c22 100644
> > > --- a/drivers/leds/trigger/ledtrig-activity.c
> > > +++ b/drivers/leds/trigger/ledtrig-activity.c
> > > @@ -57,11 +57,15 @@ static void led_activity_function(struct timer_list *t)
> > >  	curr_used = 0;
> > >  
> > >  	for_each_possible_cpu(i) {
> > > -		curr_used += kcpustat_cpu(i).cpustat[CPUTIME_USER]
> > > -			  +  kcpustat_cpu(i).cpustat[CPUTIME_NICE]
> > > -			  +  kcpustat_field(&kcpustat_cpu(i), CPUTIME_SYSTEM, i)
> > > -			  +  kcpustat_cpu(i).cpustat[CPUTIME_SOFTIRQ]
> > > -			  +  kcpustat_cpu(i).cpustat[CPUTIME_IRQ];
> > > +		struct kernel_cpustat kcpustat;
> > > +
> > > +		kcpustat_fetch_cpu(&kcpustat, i);
> > > +
> > > +		curr_used += kcpustat.cpustat[CPUTIME_USER]
> > > +			  +  kcpustat.cpustat[CPUTIME_NICE]
> > > +			  +  kcpustat.cpustat[CPUTIME_SYSTEM]
> > > +			  +  kcpustat.cpustat[CPUTIME_SOFTIRQ]
> > > +			  +  kcpustat.cpustat[CPUTIME_IRQ];
> > 
> > Not the best tested series:
> > 
> > --- a/drivers/leds/trigger/ledtrig-activity.c
> > +++ b/drivers/leds/trigger/ledtrig-activity.c
> > @@ -59,7 +59,7 @@ static void led_activity_function(struct timer_list *t)
> >  	for_each_possible_cpu(i) {
> >  		struct kernel_cpustat kcpustat;
> >  
> > -		kcpustat_fetch_cpu(&kcpustat, i);
> > +		kcpustat_cpu_fetch(&kcpustat, i);
> >  
> >  		curr_used += kcpustat.cpustat[CPUTIME_USER]
> >  			  +  kcpustat.cpustat[CPUTIME_NICE]
> > 
> > 
> > :-)
> 
> Oops, I tested with vtime on and off but that one slipped under my config.
> Do you want me to resend?

No need, I suspect this slipped in via my last minute request for that 
interface cleanup - so I just applied the fix and tested it - it all 
passed testing today and I just pushed it out into tip:sched/core.

So all's good so far.

Thanks Frederic!

	Ingo