linux-kernel - Re: [RFC/RFT][PATCH 1/7] time: tick-sched: Reorganize idle tick management code

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Date:   Mon, 5 Mar 2018 12:26:50 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        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>,
        Linux PM <linux-pm@...r.kernel.org>
Subject: Re: [RFC/RFT][PATCH 1/7] time: tick-sched: Reorganize idle tick
 management code

On Mon, Mar 5, 2018 at 11:44 AM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Sun, Mar 04, 2018 at 11:24:00PM +0100, Rafael J. Wysocki wrote:
>> +/**
>> + * 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)
>> +{
>> +     __tick_nohz_idle_prepare();
>> +
>> +     local_irq_enable();
>> +}
>
> I really dislike the asymmetry in IRQ state you introduced here.
> __tick_nohz_idle_prepare() disables IRQs. Must we do that?

Not really, but at the cost of a tiny bit of duplicated code.