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Date: Fri, 21 Jun 2013 08:38:31 -0700
From: Arjan van de Ven <arjan@linux.intel.com>
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To: Morten Rasmussen <morten.rasmussen@arm.com>
CC: David Lang <david@lang.hm>, Ingo Molnar <mingo@kernel.org>,
        "alex.shi@intel.com" <alex.shi@intel.com>,
        "peterz@infradead.org" <peterz@infradead.org>,
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        Andrew Morton <akpm@linux-foundation.org>,
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        "tglx@linutronix.de" <tglx@linutronix.de>,
        Catalin Marinas <Catalin.Marinas@arm.com>
Subject: Re: power-efficient scheduling design
References: <20130530134718.GB32728@e103034-lin> <20130531105204.GE30394@gmail.com> <20130614160522.GG32728@e103034-lin> <51C07ABC.2080704@linux.intel.com> <alpine.DEB.2.02.1306181039340.9258@nftneq.ynat.uz> <51C1D0BB.3040705@linux.intel.com> <20130619170042.GH5460@e103034-lin> <51C1E58D.9000408@linux.intel.com> <20130621085002.GJ5460@e103034-lin>
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On 6/21/2013 1:50 AM, Morten Rasmussen wrote:
>> ypically.
> A hint when a task is moved to a new cpu is too late if the migration
> shouldn't have happened at all. If the scheduler knows that the cpu is
> able to switch to a higher p-state it can decide to wait for the p-state
> change instead of migrating the task and waking up another cpu.
>

oops sorry I misread your mail (lack of early coffee I suppose)

I can see your point of having a thing for "did we ask for all the performance
we could ask for" prior to doing a load balance (although, for power efficiency,
if you have two tasks that could run in parallel, it's usually better to
run them in parallel... so likely we should balance anyway)