linux-kernel - Re: [PATCH v8 03/10] sched: idle: Do not stop the tick before cpuidle_idle

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Message-ID: <20180402212508.GB19895@lerouge>
Date:   Mon, 2 Apr 2018 23:25:09 +0200
From:   Frederic Weisbecker <frederic@...nel.org>
To:     "Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:     Linux PM <linux-pm@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.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>,
        Len Brown <len.brown@...el.com>
Subject: Re: [PATCH v8 03/10] sched: idle: Do not stop the tick before
 cpuidle_idle_call()

On Thu, Mar 29, 2018 at 02:02:24PM +0200, 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.
> 
> Second, to address the issue with short idle duration predictions
> by the idle governor after the tick has been stopped, it will be
> necessary to change the ordering of cpuidle_select() with respect
> to tick_nohz_idle_stop_tick().  To prepare for that, put a
> tick_nohz_idle_stop_tick() call in the same branch in which
> cpuidle_select() is called.
> 
> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>

Rewiewed-by: Frederic Weisbecker <frederic@...nel.org>