linux-kernel - Re: [PATCH 0/2] nohz: Avoid double clock write

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Message-ID: <20140811230018.GA1492@lerouge>
Date:	Tue, 12 Aug 2014 01:00:20 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Subject: Re: [PATCH 0/2] nohz: Avoid double clock write

Ping?

On Thu, Jul 31, 2014 at 06:45:54PM +0200, Frederic Weisbecker wrote:
> Hi Thomas,
> 
> The tick reschedules itself unconditionally. That's what we want as long
> as the CPU is in periodic mode. It's not that relevant when the CPU
> is in dynticks mode though as the clock write is likely to be overwritten
> by the nohz code on irq exit.
> 
> In low-res mode, that even result in unexpected periodic behaviour when
> no timer is scheduled in the future.
> 
> So here is a set that proposes the removal of these double writes.
> 
> git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
> 	origin/nohz/drop-double-write-v2
> 
> Thanks,
> 	Frederic
> ---
> 
> Viresh Kumar (2):
>       nohz: Fix spurious periodic tick behaviour in low-res dynticks mode
>       nohz: Avoid tick's double reprogramming in highres mode
> 
> 
>  kernel/time/tick-sched.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
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