From: Tim Chen <tim.c.chen@linux.intel.com>
Subject: Re: [PATCH v4 6/7] sched: add function nr_running_cpu to expose
 number of tasks running on cpu
Date: Tue, 15 Jul 2014 11:40:58 -0700
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Cc: Herbert Xu <herbert@gondor.apana.org.au>,
	"H. Peter Anvin" <hpa@zytor.com>,
	"David S.Miller" <davem@davemloft.net>,
	Ingo Molnar <mingo@kernel.org>,
	Chandramouli Narayanan <mouli@linux.intel.com>,
	Vinodh Gopal <vinodh.gopal@intel.com>,
	James Guilford <james.guilford@intel.com>,
	Wajdi Feghali <wajdi.k.feghali@intel.com>,
	Jussi Kivilinna <jussi.kivilinna@iki.fi>,
	linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org
To: Peter Zijlstra <peterz@infradead.org>
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On Tue, 2014-07-15 at 14:07 +0200, Peter Zijlstra wrote:
> On Tue, Jul 15, 2014 at 11:50:45AM +0200, Peter Zijlstra wrote:
> > So you already have an idle notifier (which is x86 only, we should fix
> > that I suppose), and you then double check there really isn't anything
> > else running.
> 
> Note that we've already done a large part of the expense of going idle
> by the time we call that idle notifier -- in specific, we've
> reprogrammed the clock to stop the tick.
> 
> Its really wasteful to then generate work again, which means we have to
> again reprogram the clock etc.

Will try another version of the patch without using the idle notifier.

Tim