linux-kernel - Re: [RFC PATCH v3 1/9] CPU hotplug: Provide APIs to prevent CPU offline from atomic context

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Message-ID: <20121211134758.GA7084@htj.dyndns.org>
Date:	Tue, 11 Dec 2012 05:47:58 -0800
From:	Tejun Heo <tj@...nel.org>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Oleg Nesterov <oleg@...hat.com>, tglx@...utronix.de,
	peterz@...radead.org, paulmck@...ux.vnet.ibm.com,
	rusty@...tcorp.com.au, mingo@...nel.org, akpm@...ux-foundation.org,
	namhyung@...nel.org, vincent.guittot@...aro.org, sbw@....edu,
	amit.kucheria@...aro.org, rostedt@...dmis.org, rjw@...k.pl,
	wangyun@...ux.vnet.ibm.com, xiaoguangrong@...ux.vnet.ibm.com,
	nikunj@...ux.vnet.ibm.com, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH v3 1/9] CPU hotplug: Provide APIs to prevent CPU
 offline from atomic context

Hello, Srivatsa.

On Tue, Dec 11, 2012 at 06:43:54PM +0530, Srivatsa S. Bhat wrote:
> This approach (of using synchronize_sched()) also looks good. It is simple,
> yet effective, but unfortunately inefficient at the writer side (because
> he'll have to wait for a full synchronize_sched()).

While synchornize_sched() is heavier on the writer side than the
originally posted version, it doesn't stall the whole machine and
wouldn't introduce latencies to others.  Shouldn't that be enough?

Thanks.

-- 
tejun
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