linux-kernel - Re: [RFC/RFT][PATCH v2 1/6] time: tick-sched: Reorganize idle tick management code

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Message-ID: <1938066.lrFpnYERYl@aspire.rjw.lan>
Date:   Thu, 08 Mar 2018 10:22:26 +0100
From:   "Rafael J. Wysocki" <rjw@...ysocki.net>
To:     Frederic Weisbecker <frederic@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Frederic Weisbecker <fweisbec@...il.com>,
        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: [RFC/RFT][PATCH v2 1/6] time: tick-sched: Reorganize idle tick management code

On Thursday, March 8, 2018 12:18:29 AM CET Frederic Weisbecker wrote:
> On Tue, Mar 06, 2018 at 10:02:01AM +0100, Rafael J. Wysocki wrote:
> > Index: linux-pm/kernel/time/tick-sched.c
> > ===================================================================
> > --- linux-pm.orig/kernel/time/tick-sched.c
> > +++ linux-pm/kernel/time/tick-sched.c
> > +
> > +/**
> > + * tick_nohz_idle_prepare - prepare for entering idle on the current CPU.
> > + *
> > + * Called when we start the idle loop.
> > + */
> > +void tick_nohz_idle_prepare(void)
> > +{
> > +	struct tick_sched *ts;
> > +
> > +	__tick_nohz_idle_prepare();
> > +
> > +	local_irq_disable();
> > +
> > +	ts = this_cpu_ptr(&tick_cpu_sched);
> > +	ts->inidle = 1;
> > +
> > +	local_irq_enable();
> > +}
> 
> Why not calling tick_nohz_start_idle() from there? This is going to
> simplify the rest, you won't need to call tick_nohz_idle_go_idle()
> from places that don't want to stop the tick and you can then remove
> the stop_tick argument.

So I guess I would then use ts->idle_entrytime as "now" in the
tick_nohz_get_sleep_length() computation, right?