Re: [RFC PATCH v3] tick/sched: Ensure quiet_vmstat() is called when the idle tick was stopped too
From: Aaron Tomlin
Date: Mon Apr 25 2022 - 07:39:23 EST
On Mon 2022-04-25 09:23 +0200, Christoph Lameter wrote:
> On Fri, 22 Apr 2022, Aaron Tomlin wrote:
> > A customer provided some evidence which indicates that the idle tick was
> > stopped; albeit, CPU-specific vmstat counters still remained populated.
> > Thus one can only assume quiet_vmstat() was not invoked on return to the
> > idle loop.
> Could we *always* fold the vmstat counters when entering idle mode? That
> would make the logic less complicated. There is nothing else to do since
> we are entering an idle state and if there are any counter deltas then we
> have the time to process them. This may also decrease the time that
> deltas exist significantly and an idle system will have accurate vmstat
Thank you for your feedback.
Yes, in the context of nohz, this patch should ensure it, if required, when
the idle tick is to be stopped.