linux-kernel - Re: [PATCH 1/2] sched / idle: Drop default_idle_call() fallback from call

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Message-ID: <20160118143628.GR6357@twins.programming.kicks-ass.net>
Date:	Mon, 18 Jan 2016 15:36:28 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Rafael J. Wysocki" <rjw@...ysocki.net>
Cc:	Linux PM list <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH 1/2] sched / idle: Drop default_idle_call() fallback from
 call_cpuidle()

On Sat, Jan 16, 2016 at 12:54:53AM +0100, Rafael J. Wysocki wrote:
> This eliminates one branch from the idle loop and makes the governors
> and find_deepest_state() handle the case when all states have been
> disabled from sysfs consistently.

> Index: linux-pm/kernel/sched/idle.c
> ===================================================================
> --- linux-pm.orig/kernel/sched/idle.c
> +++ linux-pm/kernel/sched/idle.c
> @@ -97,12 +97,6 @@ void default_idle_call(void)
>  static int call_cpuidle(struct cpuidle_driver *drv, struct cpuidle_device *dev,
>  		      int next_state)
>  {
> -	/* Fall back to the default arch idle method on errors. */
> -	if (next_state < 0) {
> -		default_idle_call();
> -		return next_state;
> -	}
> -
>  	/*
>  	 * The idle task must be scheduled, it is pointless to go to idle, just
>  	 * update no idle residency and return.


Acked-by: Peter Zijlstra (Intel) <peterz@...radead.org>