Messages in this thread | | | Date | Tue, 10 Jan 2012 16:32:44 +0100 | Subject | Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken | From | Vincent Guittot <> |
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On 10 January 2012 15:32, Arjan van de Ven <arjan@linux.intel.com> wrote: > On 1/10/2012 1:18 AM, Ingo Molnar wrote: >> >> * Suresh Siddha <suresh.b.siddha@intel.com> wrote: >> >>> On Tue, 2012-01-10 at 00:58 -0500, Youquan Song wrote: >>>> Thanks Peter! Here is the patch. >>> >>> Youquan, As far as I know both the >>> sched_smt_power_savings/sched_mc_power_savings are broken for atleast an >>> year. >> >> We want a single knob, sched_power_savings - with the mc_ and >> smt_ ones still kept and aliased to sched_power_savings, for >> compatibility reasons. >> >> As Peter said, the other reasonable option is to have no knob at >> all and restart this code from scratch. >> >> The other thing we should do is to add sane defaults: to turn on >> sched_power_savings *AUTOMATICALLY* when a system is obviously >> battery driven and turn it off when the system is obviously AC >> driven. User-space can still implement policy and override the >> kernel's default, but there's absolutely no excuse to not offer >> this default ourselves. > > a very good default would be to keep all tasks on one package until half > the cores in the package are busy, and then start spreading out. >
The choice of spreading or not tasks is clearly architecture or even platform dependent. Can't we get such optimal threshold information from architecture code ?
> I suspect that'll be the 90% case coverage. > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.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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