linux-kernel - Re: [PATCH V3 4/7] PHYLIB: queue work on any cpu

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Message-Id: <20130318.133339.2056938599662437643.davem@davemloft.net>
Date:	Mon, 18 Mar 2013 13:33:39 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	viresh.kumar@...aro.org
Cc:	pjt@...gle.com, paul.mckenney@...aro.org, tglx@...utronix.de,
	tj@...nel.org, suresh.b.siddha@...el.com, venki@...gle.com,
	mingo@...hat.com, peterz@...radead.org, rostedt@...dmis.org,
	linaro-kernel@...ts.linaro.org, robin.randhawa@....com,
	Steve.Bannister@....com, Liviu.Dudau@....com,
	charles.garcia-tobin@....com, Arvind.Chauhan@....com,
	linux-rt-users@...r.kernel.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org
Subject: Re: [PATCH V3 4/7] PHYLIB: queue work on any cpu

From: Viresh Kumar <viresh.kumar@...aro.org>
Date: Mon, 18 Mar 2013 20:53:26 +0530

> Phylib uses workqueues for multiple purposes. There is no real dependency of
> scheduling these on the cpu which scheduled them.
> 
> On a idle system, it is observed that and idle cpu wakes up many times just to
> service this work. It would be better if we can schedule it on a cpu which isn't
> idle to save on power.
> 
> By idle cpu (from scheduler's perspective) we mean:
> - Current task is idle task
> - nr_running == 0
> - wake_list is empty
> 
> This patch replaces the schedule_work() and schedule_delayed_work() routines
> with their queue_[delayed_]work_on_any_cpu() siblings with system_wq as
> parameter.
> 
> These routines would look for the closest (via scheduling domains) non-idle cpu
> (non-idle from schedulers perspective). If the current cpu is not idle or all
> cpus are idle, work will be scheduled on local cpu.
> 
> Cc: "David S. Miller" <davem@...emloft.net>
> Cc: netdev@...r.kernel.org
> Signed-off-by: Viresh Kumar <viresh.kumar@...aro.org>

This will need to be applied to whatever tree adds these new interfaces,
and for that:

Acked-by: David S. Miller <davem@...emloft.net>
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