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Date: Tue, 24 Mar 2015 16:53:52 +0100 From: Peter Zijlstra <peterz@...radead.org> To: Morten Rasmussen <morten.rasmussen@....com> Cc: "mingo@...hat.com" <mingo@...hat.com>, "vincent.guittot@...aro.org" <vincent.guittot@...aro.org>, Dietmar Eggemann <Dietmar.Eggemann@....com>, "yuyang.du@...el.com" <yuyang.du@...el.com>, "preeti@...ux.vnet.ibm.com" <preeti@...ux.vnet.ibm.com>, "mturquette@...aro.org" <mturquette@...aro.org>, "nico@...aro.org" <nico@...aro.org>, "rjw@...ysocki.net" <rjw@...ysocki.net>, Juri Lelli <Juri.Lelli@....com>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org> Subject: Re: [RFCv3 PATCH 33/48] sched: Energy-aware wake-up task placement On Tue, Mar 24, 2015 at 03:42:42PM +0000, Morten Rasmussen wrote: > Right, I agree that we should preferably do the normal thing for U ~= 1. > We can restructure the wake-up path to follow that pattern, but we need > to know U beforehand to choose the right path. U isn't just > get_cpu_usage(prev_cpu) but some broader view of the of the cpu > utilizations. For example, prev_cpu might be full, but everyone else is > idle so we still want to try to do an energy aware wake-up on some other > cpu. U could be the minium utilization of all cpus in prev_cpu's > sd_llc, which is somewhat similar to what energy_aware_wake_cpu() does. Yeah, or a setting in the root domain set by the regular periodic load balancer; that already grew some mojo to determine this in a patch I recently commented on. > I guess energy_aware_wake_cpu() could be refactored to call > select_idle_sibling() if it find U ~= 1? Sure yeah, that's not the hard part I think. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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