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: Mon, 14 Jul 2014 10:51:31 -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>,
	Peter Zijlstra <peterz@infradead.org>,
	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: tkhai@yandex.ru
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On Sat, 2014-07-12 at 13:25 +0400, Kirill Tkhai wrote:

> >  
> > +unsigned long nr_running_cpu(int cpu)
> > +{
> > +	if (cpumask_test_cpu(cpu, cpu_online_mask))
> > +		return cpu_rq(cpu)->nr_running;
> > +	else
> > +		return 0;
> > +}
> > +
> 
> Offline cpu should have nr_running equal to 0. We park last
> enqueued thread (migration_thread) at the end of take_cpu_down().
> 
> So, it's enough to return cpu_rq(cpu)->nr_running.

Thanks.  This seems reasonable.

Tim