linux-kernel - Re: [RFC][PATCH 4/7] sched: power: Remove power capacity hints for kworker threads

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Date:	Mon, 14 Oct 2013 18:19:09 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	"mingo@...nel.org" <mingo@...nel.org>,
	"pjt@...gle.com" <pjt@...gle.com>, "rjw@...k.pl" <rjw@...k.pl>,
	"dirk.j.brandewie@...el.com" <dirk.j.brandewie@...el.com>,
	"vincent.guittot@...aro.org" <vincent.guittot@...aro.org>,
	"alex.shi@...aro.org" <alex.shi@...aro.org>,
	"preeti@...ux.vnet.ibm.com" <preeti@...ux.vnet.ibm.com>,
	"efault@....de" <efault@....de>, "corbet@....net" <corbet@....net>,
	"tglx@...utronix.de" <tglx@...utronix.de>,
	Catalin Marinas <Catalin.Marinas@....com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-kernel@...ts.linaro.org" <linaro-kernel@...ts.linaro.org>
Subject: Re: [RFC][PATCH 4/7] sched: power: Remove power capacity hints for
 kworker threads

On Mon, Oct 14, 2013 at 05:13:11PM +0100, Arjan van de Ven wrote:
> On 10/14/2013 9:10 AM, Morten Rasmussen wrote:
> > On Mon, Oct 14, 2013 at 02:33:56PM +0100, Peter Zijlstra wrote:
> >> On Fri, Oct 11, 2013 at 06:19:14PM +0100, Morten Rasmussen wrote:
> >>> Removing power hints for kworker threads enables easier use of
> >>> workqueues in the power driver late callback. That would otherwise
> >>> lead to an endless loop unless it is prevented in the power driver.
> >>
> >> There's many kworker users; some of them actually consume lots of
> >> cputime. Therefore how did you come to the conclusion that excepting all
> >> users was the better choice of a little added complexity in the one
> >> place where it actually matters?
> >
> > Agreed that it is not ideal. I will find a better solution for this
> > problem.
> >
> 
> can you explain which architectures we're talking about that need this?
> is it only old stuff, or is there anything current ?
> 

For now I need it for the cpufreq wrapper governor. I hope it can be
avoided for native power drivers, but I don't have a complete overview
of all architectures yet.

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