Re: [PATCH RESEND] sched/nohz: Affine unpinned timers to housekeepers

From: Mike Galbraith
Date: Mon Aug 24 2015 - 03:54:55 EST


On Mon, 2015-08-24 at 09:41 +0200, Ingo Molnar wrote:
> * Mike Galbraith <umgwanakikbuti@xxxxxxxxx> wrote:
>
> > On Mon, 2015-08-24 at 08:44 +0200, Ingo Molnar wrote:
> >
> > > the 'housekeeping CPU' is essentially the boot CPU. Yet we dedicate a full mask to
> > > it (housekeeping_mask - a variable mask to begin with) and recover the
> > > housekeeping CPU via:
> > >
> > > + return cpumask_any_and(housekeeping_mask, cpu_online_mask);
> >
> > There can be, and had better be if box is big, multiple housekeepers.
>
> Yes - but that does not seem to be possible via the code right now AFAICS, so at
> minimum it's incomplete.

In master housekeepers are set up in tick_nohz_init(). Everybody who's
not a nohz_full CPU is a housekeeper.

-Mike

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