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Re: [PATCH-for-4.17] xen/sched: fix restore_vcpu_affinity() by removing it
- To: xen-devel@xxxxxxxxxxxxxxxxxxxx
- From: Juergen Gross <jgross@xxxxxxxx>
- Date: Fri, 21 Oct 2022 09:06:06 +0200
- Cc: Jan Beulich <jbeulich@xxxxxxxx>, Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, Roger Pau Monné <roger.pau@xxxxxxxxxx>, Wei Liu <wl@xxxxxxx>, George Dunlap <george.dunlap@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>, Stefano Stabellini <sstabellini@xxxxxxxxxx>, Dario Faggioli <dfaggioli@xxxxxxxx>, Henry Wang <Henry.Wang@xxxxxxx>, Marek Marczykowski-Górecki <marmarek@xxxxxxxxxxxxxxxxxxxxxx>
- Delivery-date: Fri, 21 Oct 2022 07:06:17 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 21.10.22 08:58, Juergen Gross wrote:
When the system is coming up after having been suspended,
restore_vcpu_affinity() is called for each domain in order to adjust
the vcpu's affinity settings in case a cpu didn't come to live again.
The way restore_vcpu_affinity() is doing that is wrong, because the
specific scheduler isn't being informed about a possible migration of
the vcpu to another cpu. Additionally the migration is often even
happening if all cpus are running again, as it is done without check
whether it is really needed.
As cpupool management is already calling cpu_disable_scheduler() for
cpus not having come up again, and cpu_disable_scheduler() is taking
care of eventually needed vcpu migration in the proper way, there is
simply no need for restore_vcpu_affinity().
So just remove restore_vcpu_affinity() completely.
Fixes: 8a5d50dd0b04 ("xen: sched: simplify ACPI S3 resume path.")
This Fixes: tag is wrong. It should be:
Fixes: 8a04eaa8ea83 ("xen/sched: move some per-vcpu items to struct sched_unit")
Juergen
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