Messages in this thread | | | From | Catalin Marinas <> | Date | Fri, 21 Jun 2013 22:23:25 +0100 | Subject | Re: power-efficient scheduling design |
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On 21 June 2013 16:38, Arjan van de Ven <arjan@linux.intel.com> wrote: > On 6/21/2013 1:50 AM, Morten Rasmussen wrote: >> 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)
Not necessarily, especially if parallel running implies powering up a full cluster just for one CPU (it depends on the hardware but for example a cluster may not be able to go in deeper sleep states unless all the CPUs in that cluster are idle).
-- Catalin
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