linux-kernel - Re: [PATCH] tick-sched: fix idle and iowait sleeptime accounting vs CPU hotplug

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Message-ID: <Za7swp31JRzGJwzS@pavilion.home>
Date: Mon, 22 Jan 2024 23:31:30 +0100
From: Frederic Weisbecker <frederic@...nel.org>
To: Tim Chen <tim.c.chen@...ux.intel.com>
Cc: Heiko Carstens <hca@...ux.ibm.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Vasily Gorbik <gor@...ux.ibm.com>, linux-kernel@...r.kernel.org,
	linux-s390@...r.kernel.org
Subject: Re: [PATCH] tick-sched: fix idle and iowait sleeptime accounting vs
 CPU hotplug

Le Mon, Jan 22, 2024 at 10:19:30AM -0800, Tim Chen a écrit :
> On Mon, 2024-01-15 at 17:35 +0100, Heiko Carstens wrote:
> > 
> >  
> > +	idle_sleeptime = ts->idle_sleeptime;
> > +	iowait_sleeptime = ts->iowait_sleeptime;
> >  	memset(ts, 0, sizeof(*ts));
> > +	ts->idle_sleeptime = idle_sleeptime;
> > +	ts->iowait_sleeptime = iowait_sleeptime;
> >  }
> 
> Should idle_calls and idle_sleeps be preserved and
> restored too?  
> 
> Seems like if we preserve the
> idle_sleeptime, and wish to compute the average
> sleep time per sleep, we will need to know the value of
> idle_sleeps that's also preserved across CPU offline/online.

I guess those can be saved as well. Would you like to send the patch?

Thanks.

> 
> Tim