Re: [PATCH 4/5] sched: Guarantee new group-entities always haveweight

From: Peter Zijlstra
Date: Wed Oct 16 2013 - 18:22:39 EST


On Wed, Oct 16, 2013 at 03:16:44PM -0700, Paul Turner wrote:
> > Hurm.. this gives new groups a massive weight; nr_cpus * NICE_0. ISTR
> > there being some issues with this; or was that on the wakeup path where
> > a task woke on a cpu who's group entity had '0' load because it used to
> > run on another cpu -- I can't remember.
>
> This could also arbitrarily be MIN_WEIGHT.
>
> I don't think it actually matters, in practice the set of conditions
> for this weight to ever see use are very specific (e.g. the race
> described above). Otherwise it's always going to be re-initialized (on
> first actual enqueue) to the right value. (NICE_0_LOAD seemed to make
> sense since this is what you'd "expect" for a new, single thread,
> autogroup/group.)

Fair enough. Thanks!
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