linux-kernel - Re: [RFT][PATCH v4 3/7] sched: idle: Do not stop the tick before cpuidle_idle

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Message-ID: <20180316141719.GB20981@lerouge>
Date:   Fri, 16 Mar 2018 15:17:20 +0100
From:   Frederic Weisbecker <frederic@...nel.org>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Frederic Weisbecker <fweisbec@...il.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Paul McKenney <paulmck@...ux.vnet.ibm.com>,
        Thomas Ilsche <thomas.ilsche@...dresden.de>,
        Doug Smythies <dsmythies@...us.net>,
        Rik van Riel <riel@...riel.com>,
        Aubrey Li <aubrey.li@...ux.intel.com>,
        Mike Galbraith <mgalbraith@...e.de>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [RFT][PATCH v4 3/7] sched: idle: Do not stop the tick before
 cpuidle_idle_call()

On Thu, Mar 15, 2018 at 10:12:57PM +0100, Rafael J. Wysocki wrote:
> On Thu, Mar 15, 2018 at 9:41 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> > On Thu, Mar 15, 2018 at 7:19 PM, Frederic Weisbecker
> > <frederic@...nel.org> wrote:
> >> On Mon, Mar 12, 2018 at 10:53:25AM +0100, Rafael J. Wysocki wrote:
> >>> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> >>>
> >>> Make cpuidle_idle_call() decide whether or not to stop the tick.
> >>>
> >>> First, the cpuidle_enter_s2idle() path deals with the tick (and with
> >>> the entire timekeeping for that matter) by itself and it doesn't need
> >>> the tick to be stopped beforehand.
> >>
> >> Not sure you meant timekeeping either :)
> >
> > Yeah, I meant nohz.
> 
> Well, not really. :-)
> 
> It is the entire timekeeping this time, as it can be suspended
> entirely in that code path.

Fair point.

Thanks!