Messages in this thread | | | Subject | Re: [RFC PATCH v3 3/6] sched: pack small tasks | From | Peter Zijlstra <> | Date | Wed, 27 Mar 2013 09:46:20 +0100 |
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On Tue, 2013-03-26 at 08:29 -0700, Arjan van de Ven wrote: > > Isn't this basically related to picking the NO_HZ cpu; if the system > > isn't fully symmetric with its power gates you want the NO_HZ cpu to be > > the 'special' cpu. If it is symmetric we really don't care which core > > is left 'running' and we can even select a new pack cpu from the idle > > cores once the old one is fully utilized. > > you don't really care much sure, but there's some advantages for sorting "all the way left", > e.g. to linux cpu 0. > Some tasks only run there, and interrupts tend to be favored to that cpu as well on x86.
Right, and I suspect all the big-little nonsense will have the little cores on low numbers as well (is this architected or can a creative licensee screw us over?)
So find_new_ilb() already does cpumask_first(), so it has a strong leftmost preference. We just need to make sure it indeed does the right thing and doesn't have some unintended side effect.
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