linux-kernel - Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for short idle periods

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Message-ID: <20170712121950.zfcoyjnduxxgat2m@hirez.programming.kicks-ass.net>
Date:   Wed, 12 Jul 2017 14:19:50 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Frederic Weisbecker <fweisbec@...il.com>
Cc:     "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        Aubrey Li <aubrey.li@...el.com>, tglx@...utronix.de,
        len.brown@...el.com, rjw@...ysocki.net, ak@...ux.intel.com,
        tim.c.chen@...ux.intel.com, arjan@...ux.intel.com,
        yang.zhang.wz@...il.com, x86@...nel.org,
        linux-kernel@...r.kernel.org, Aubrey Li <aubrey.li@...ux.intel.com>
Subject: Re: [RFC PATCH v1 04/11] sched/idle: make the fast idle path for
 short idle periods

On Tue, Jul 11, 2017 at 06:33:55PM +0200, Frederic Weisbecker wrote:
>     if (!tick_nohz_full_cpu(smp_processor_id()) && likely(predicted_idle_us < short_idle_threshold))
>         cpuidle_fast();
> 
> Ugly but safer!

I'd not overly worry about this, cpuidle_fast() isn't anything that's
likely to ever happen.