linux-kernel - Re: [PATCH 07/13] sched: Enable IPI reception on timekeeper under nohz full system

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Message-ID: <20131218100615.GN13532@twins.programming.kicks-ass.net>
Date:	Wed, 18 Dec 2013 11:06:15 +0100
From:	Peter Zijlstra <peterz@...radead.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...nel.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
	John Stultz <john.stultz@...aro.org>,
	Alex Shi <alex.shi@...aro.org>,
	Kevin Hilman <khilman@...aro.org>
Subject: Re: [PATCH 07/13] sched: Enable IPI reception on timekeeper under
 nohz full system

On Tue, Dec 17, 2013 at 11:51:26PM +0100, Frederic Weisbecker wrote:
> We need the default timekeeping CPU to be able to receive IPIs sent
> from full dynticks CPUs when they wake up from full system idle state.
> 
> Therefore we need an entrypoint from the scheduler IPI so that the
> need to poll on timekeeping duty is re-evaluated from irq_exit().
> 
> In order to achieve this, lets take the scheduler IPI everytime as long
> as there is at least one full dynticks CPU around. Full dynticks CPUs
> are interested too in taking scheduler IPIs to reevaluate their tick.

I should probably read the other patches in this series, but the above
makes my brain go *beeeep* and throw an error.


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