Messages in this thread | | | Date | Mon, 24 Aug 2015 10:00:11 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH RESEND] sched/nohz: Affine unpinned timers to housekeepers |
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* Mike Galbraith <umgwanakikbuti@gmail.com> wrote:
> On Mon, 2015-08-24 at 09:41 +0200, Ingo Molnar wrote: > > * Mike Galbraith <umgwanakikbuti@gmail.com> 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.
Ah, indeed, I missed the nohz_full= boot option:
static int __init tick_nohz_full_setup(char *str) { alloc_bootmem_cpumask_var(&tick_nohz_full_mask); if (cpulist_parse(str, tick_nohz_full_mask) < 0) {
Ok, first question is resolved - but the second one, behavior on boot CPU unplug still holds.
Thanks,
Ingo
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