linux-kernel - Re: [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock

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Message-ID: <20130820153524.GC17441@somewhere>
Date:	Tue, 20 Aug 2013 17:35:26 +0200
From:	Frederic Weisbecker <fweisbec@...il.com>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Fernando Luis Vázquez Cao 
	<fernando_b1@....ntt.co.jp>, Oleg Nesterov <oleg@...hat.com>,
	Ingo Molnar <mingo@...nel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	LKML <linux-kernel@...r.kernel.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 2/4] nohz: Synchronize sleep time stats with seqlock

On Tue, Aug 20, 2013 at 08:33:50AM -0700, Arjan van de Ven wrote:
> On 8/20/2013 8:29 AM, Frederic Weisbecker wrote:
> 
> >>
> >>Of course, if we can get away with completely removing all of that
> >>(which I think Arjan suggested was a real possibility) then that would
> >>be ever so much better still :-)
> >
> >Would be lovely. But I don't know much about cpufreq, I hope somebody who's
> >familiar with that code can handle this. Then once there are no more users
> >of get_cpu_iowait_sleep_time() I can simply zap and clean the tick/time related
> >code.
> 
> it's just doing the "idle = 100 - busy% - iowait%" calculation.
> (with the later part only for Intel cpus iirc)
> 
> in a perfect world the scheduler would be doing that calculation in the first place ;-)
> 
> removing the later part will impact performance some on specific workloads,
> but most Intel cpus that this applies to should not be using cpufreq anymore
> anyway.

Are there other users than intel?
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