* Mike Galbraith <umgwanakikb...@gmail.com> wrote:
> On Mon, 2015-08-24 at 09:41 +0200, Ingo Molnar wrote:
> > * Mike Galbraith <umgwanakikb...@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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