From: sashiko-bot@kernel.org
To: "Yury Norov" <ynorov@nvidia.com>
Cc: linux-s390@vger.kernel.org, "Heiko Carstens" <hca@linux.ibm.com>,
"Vasily Gorbik" <gor@linux.ibm.com>,
"Alexander Gordeev" <agordeev@linux.ibm.com>,
"Christian Borntraeger" <borntraeger@linux.ibm.com>
Subject: Re: [PATCH 2/7] sched: restore preferred CPUs when hotplug removes the last one
Date: Fri, 13 Nov 2026 19:12:45 +0000 [thread overview]
Message-ID: <sashiko-outbox-213525@kernel.org> (raw)
In-Reply-To: <20261113184257.621707-3-ynorov@nvidia.com>
> Offlining the last preferred CPU leaves cpu_preferred_mask empty. Normal
> fair load balancing stops, potentially leaving CPUs idle while having
> queued tasks.
>
> Currently, steal governor is the only module that may modify the mask,
> so it takes care of it by resetting the mask to mirror the active cpumask.
>
> The design allows alternative preferred cpumask managers; relying on
> loadable modules to maintain consistency of the core data structure
> is not worthwhile in general.
>
> Restore all remaining active CPUs as preferred in sched_cpu_deactivate()
> path, without relying on the steal governor to recover.
>
> Signed-off-by: Yury Norov <ynorov@nvidia.com>
Sashiko has reviewed this patch and found no issues.
--
Sashiko AI review · https://sashiko.dev/#/patchset/20261113184257.621707-2-ynorov@nvidia.com?part=2
next prev parent reply other threads:[~2026-11-13 19:12 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20261113184257.621707-1-ynorov@nvidia.com>
2026-11-13 18:42 ` [PATCH 1/7] cpumask: add reset_preferred_cpumask() helper Yury Norov
2026-11-13 18:55 ` sashiko-bot
2026-11-13 18:42 ` [PATCH 2/7] sched: restore preferred CPUs when hotplug removes the last one Yury Norov
2026-11-13 19:12 ` sashiko-bot [this message]
2026-11-13 18:42 ` [PATCH 3/7] virt: steal_governor: remove the minimum elapsed-time check Yury Norov
2026-11-13 18:56 ` sashiko-bot
2026-11-13 18:42 ` [PATCH 4/7] virt: steal_governor: serialize sampling against CPU hotplug Yury Norov
2026-11-13 19:03 ` sashiko-bot
2026-11-13 18:42 ` [PATCH 5/7] virt: steal_governor: warn on unexpected preferred mask states Yury Norov
2026-11-13 19:06 ` sashiko-bot
2026-11-13 18:42 ` [PATCH 6/7] virt: steal_governor: restart sampling immediately after CPU hotplug Yury Norov
2026-11-13 18:42 ` [PATCH 7/7] cpu: make preferred CPU policy writers mutually exclusive Yury Norov
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