linux-kernel - Re: [PATCH 5/8] nohz: Restart the tick from irq exit

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Message-ID: <20150612125941.GX19282@twins.programming.kicks-ass.net>
Date:	Fri, 12 Jun 2015 14:59:41 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Frederic Weisbecker <fweisbec@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>,
	Christoph Lameter <cl@...ux.com>,
	Ingo Molnar <mingo@...nel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 5/8] nohz: Restart the tick from irq exit

On Fri, Jun 12, 2015 at 02:38:36PM +0200, Frederic Weisbecker wrote:
> On Fri, Jun 12, 2015 at 09:32:45AM +0200, Peter Zijlstra wrote:
> > On Thu, Jun 11, 2015 at 07:36:05PM +0200, Frederic Weisbecker wrote:
> > > Restart the tick when necessary from the irq exit path. It makes nohz
> > > full more flexible and allow it to piggyback the tick restart on the
> > > scheduler IPI in the future instead of sending a dedicated IPI that
> > > often doubles the scheduler IPI on task wakeup. This will require
> > > careful review of resched_curr() callers.
> > 
> > This seems to assume schedule_ipi() callers use irq_exit(), this is
> > false.
> 
> Indeed there will be that too. Note the current patch doesn't yet rely on
> schedule_ipi(), we are still using the nohz ipis.

Ah, then I just didn't understand your changelog right.
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