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

From: Mike Galbraith
Date: Mon Aug 24 2015 - 03:23:30 EST

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.

Imagine a NO_HZ_FULL_ALL kernel on an SGI beast from hell. Offloading
8191 CPUs onto poor little CPU0 probably wouldn't work out well :)


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