Message-ID: <5034D878.1000305@linux.intel.com>
Date: Wed, 22 Aug 2012 06:02:48 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Mike Galbraith <efault@gmx.de>
CC: Alan Cox <alan@lxorguk.ukuu.org.uk>, Ingo Molnar <mingo@kernel.org>,
        Matthew Garrett <mjg59@srcf.ucam.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>, Alex Shi <alex.shi@intel.com>,
        Suresh Siddha <suresh.b.siddha@intel.com>, vincent.guittot@linaro.org,
        svaidy@linux.vnet.ibm.com, Andrew Morton <akpm@linux-foundation.org>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>, Paul Turner <pjt@google.com>
Subject: Re: [discussion]sched: a rough proposal to enable power saving in
 scheduler
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On 8/21/2012 10:41 PM, Mike Galbraith wrote:
> On Tue, 2012-08-21 at 17:02 +0100, Alan Cox wrote:
> 
>> I'd like to see actual numbers and evidence on a wide range of workloads
>> the spread/don't spread thing is even measurable given that you've also
>> got to factor in effects like completing faster and turning everything
>> off. I'd *really* like to see such evidence on a laptop,which is your
>> one cited case it might work.
> 
> For my dinky dual core laptop, I suspect you're right, but for a more
> powerful laptop, I'd expect spread/don't to be noticeable.

yeah if you don't spread, you will waste some power.
but.. current linux behavior is to spread.
so we can only make it worse.


> 
> Yeah, hard numbers would be nice to see.
> 
> If I had a powerful laptop, I'd kill irq balancing, and all but periodic
> load balancing, and expect to see a positive result. 

I'd expect to see a negative result ;-)

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