Re: [PATCH v9 3/8] cpuset: Rebuild root domain deadline accounting information

Qais Yousef
2022-12-20T11:43:09Z

On 12/19/22 09:07, Vincent Guittot wrote:
> On Sat, 17 Dec 2022 at 00:35, Qais Yousef <qyousef-wp2msK0BRk8tq7phqP6ubQ@public.gmane.org> wrote:
> >
> > Hi
> >
> > On 07/19/19 15:59, Juri Lelli wrote:
> > > When the topology of root domains is modified by CPUset or CPUhotplug
> > > operations information about the current deadline bandwidth held in the
> > > root domain is lost.
> > >
> > > This patch addresses the issue by recalculating the lost deadline
> > > bandwidth information by circling through the deadline tasks held in
> > > CPUsets and adding their current load to the root domain they are
> > > associated with.
> > >
> > > Signed-off-by: Mathieu Poirier <mathieu.poirier-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>
> > > Signed-off-by: Juri Lelli <juri.lelli-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
> > > ---
> >
> > We see that rebuild_root_domain() can take 10+ ms (I get a max of 20ms quite
> > consistently) on suspend/resume.
> >
> > Do we actually need to rebuild_root_domain() if we're going through
> > a suspend/resume cycle?
>
> During suspend to ram, there are cpus hotplug operation but If you use
> suspend to idle, you will skip cpus hotplug operation and its
> associated rebuild.

Thanks Vincent. I'll check on that - but if we want to keep suspend to ram?
Do we really to incur this hit?

Thanks