Re: [RFC PATCH v2 4/8] tick/nohz: keep tick on for a fast idle

Mike Galbraith
2017-10-16T06:26:21Z

On Mon, 2017-10-16 at 13:34 +0800, Li, Aubrey wrote:
> On 2017/10/16 12:45, Mike Galbraith wrote:
> > On Mon, 2017-10-16 at 11:26 +0800, Li, Aubrey wrote:
> >>
> >> I'll try to move quiet_vmstat() into the normal idle branch if this patch series
> >> are reasonable. Is fast_idle a good indication for it?
> >
> > see x86_tip 62cb1188ed86 sched/idle: Move quiet_vmstate() into the NOHZ code
>
> It looks like this commit makes tick stop critical as it can be invoked in interrupt
> exit path?

do_idle() ain't critical?  It is in my book.  Hopefully, you're about
to make that idle_stat.fast_idle thingy liberal enough that we cease
mucking about with the tick on every microscopic idle (and I can then
trash my years old local patch to avoid needlessly eating that cost).

-Mike