linux-kernel - Re: [PATCH v2 1/2] sched: let the scheduler see CPU idle states

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Message-ID: <20140918231544.GN2848@worktop.localdomain>
Date:	Fri, 19 Sep 2014 01:15:44 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
Cc:	Nicolas Pitre <nicolas.pitre@...aro.org>,
	Ingo Molnar <mingo@...hat.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org
Subject: Re: [PATCH v2 1/2] sched: let the scheduler see CPU idle states

On Thu, Sep 18, 2014 at 10:39:25AM -0700, Paul E. McKenney wrote:
> On Thu, Sep 18, 2014 at 10:37:33AM -0700, Paul E. McKenney wrote:

> > A stop_cpus() will force a context switch on all CPUs, though it is
> > a rather big hammer.
> 
> And I was reminded by the very next email that kick_all_cpus_sync() is
> another possibility -- it forces an interrupt on all online CPUs, idle
> or not.

I actually have a patch
http://lkml.kernel.org/r/1409815075-4180-2-git-send-email-chuansheng.liu@intel.com
that changes that, because apparently there are idle loops that don't
actually exit on interrupt :-)

But yes, something like the wake_up_all_idle_cpus() should do.
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