linux-kernel - Re: [PATCH V2 0/2] cpufreq/powernv: Set core pstate to a minimum just before hotplugging it out

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Message-ID: <7863288.1rO87QF8NW@vostro.rjw.lan>
Date:	Tue, 09 Sep 2014 02:16:03 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Preeti U Murthy <preeti@...ux.vnet.ibm.com>
Cc:	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Dirk Brandewie <dirk.j.brandewie@...el.com>,
	Shreyas Prabhu <shreyas@...ux.vnet.ibm.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Patrick Marlier <patrick.marlier@...il.com>,
	"linuxppc-dev@...abs.org" <linuxppc-dev@...abs.org>,
	Dirk Brandewie <dirk.brandewie@...il.com>,
	Vaidyanathan Srinivasan <svaidy@...ux.vnet.ibm.com>
Subject: Re: [PATCH V2 0/2] cpufreq/powernv: Set core pstate to a minimum just before hotplugging it out

On Friday, September 05, 2014 01:11:22 PM Viresh Kumar wrote:
> On 5 September 2014 13:09, Preeti U Murthy <preeti@...ux.vnet.ibm.com> wrote:
> > Today cpus go to winkle when they are offlined. Since it is the deepest
> > idle state that we have, it is expected to save good amount of power as compared
> > to online state, where cores can enter nap/fastsleep only which are
> > shallower idle states.
> > However we observed no powersavings with winkle as compared to nap/fastsleep
> > and traced the problem to the pstate of the core being kept at a high even
> > when the core is offline. This can keep the socket pstate high, thus burning
> > power unnecessarily. This patchset fixes this issue.
> >
> > Changes in V2: Changed smp_call_function_any() to smp_call_function_single() in Patch[2/2]
> 
> Acked-by: Viresh Kumar <viresh.kumar@...aro.org>

I've queued up the two patches for 3.18, thanks!

-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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