Messages in this thread | | | Date | Tue, 10 Jan 2012 06:32:16 -0800 | From | Arjan van de Ven <> | Subject | Re: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken |
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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.
I suspect that'll be the 90% case coverage.
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