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From: Henry Wang <Henry.Wang@arm.com>
To: Dario Faggioli <dfaggioli@suse.com>,
	Juergen Gross <jgross@suse.com>,
	"xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "marmarek@invisiblethingslab.com"
	<marmarek@invisiblethingslab.com>,
	"george.dunlap@citrix.com" <george.dunlap@citrix.com>,
	"mengxu@cis.upenn.edu" <mengxu@cis.upenn.edu>
Subject: RE: [PATCH-for-4.17 v3] xen/sched: migrate timers to correct cpus after suspend
Date: Fri, 4 Nov 2022 07:50:14 +0000	[thread overview]
Message-ID: <AS8PR08MB79912AF4BEC094E1EE690E93923B9@AS8PR08MB7991.eurprd08.prod.outlook.com> (raw)
In-Reply-To: <5321a4ce8c3b450c89938aae90d57d191b3791fa.camel@suse.com>

Hi Juergen,

> On Wed, 2022-11-02 at 16:00 +0100, Juergen Gross wrote:
> > Today all timers are migrated to cpu 0 when the system is being
> > suspended. They are not migrated back after resuming the system
> > again.
> >
> > This results (at least) to visible problems with the credit
> > scheduler,
> > as the timer isn't handled on the cpu it was expected to occur, which
> > will result in an ASSERT() triggering. Other more subtle problems,
> > like
> > uninterrupted elongated time slices, are probable. The least effect
> > will be worse performance on cpu 0 resulting from most scheduling
> > related timer interrupts happening there after suspend/resume.
> >
> > Add migrating the scheduling related timers of a specific cpu from
> > cpu
> > 0 back to its original cpu when that cpu has gone up when resuming
> > the
> > system.
> >
> > Fixes: 0763cd268789 ("xen/sched: don't disable scheduler on cpus
> > during suspend")
> > Signed-off-by: Juergen Gross <jgross@suse.com>
> > Tested-by: Marek Marczykowski-Górecki
> > <marmarek@invisiblethingslab.com>
> >
> Acked-by: Dario Faggioli <dfaggioli@suse.com>

Release-acked-by: Henry Wang <Henry.Wang@arm.com>

Kind regards,
Henry

      reply	other threads:[~2022-11-04  7:50 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-11-02 15:00 [PATCH-for-4.17 v3] xen/sched: migrate timers to correct cpus after suspend Juergen Gross
2022-11-04  7:48 ` Dario Faggioli
2022-11-04  7:50   ` Henry Wang [this message]

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