Re: [PATCH 1/5] cgroup/cpuset: Skip task update if hotplug doesn't affect current cpuset

From: Waiman Long
Date: Tue Mar 14 2023 - 14:21:52 EST



On 3/14/23 12:50, Michal Koutný wrote:
On Mon, Mar 06, 2023 at 03:08:45PM -0500, Waiman Long <longman@xxxxxxxxxx> wrote:
If a hotplug event doesn't affect the current cpuset, there is no point
to call hotplug_update_tasks() or hotplug_update_tasks_legacy(). So
just skip it.
This skips "insane" modification of cs->cpus_allowed in
hotplug_update_tasks_legacy() but assuming cs->cpus_allowed is kept in
sync with cs->effective_cpus on v1, it is OK to skip the update based
only on effective_cpus check.

Yes, effective_cpus is equivalent to cpus_allowed in v1 unless you mount the cpuset with the cpuset_v2_mode flag which will behave more like v2 where effective_cpus is still the key.

Cheers,
Longman