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cgroup/cpuset: avoid unneeded cpuset_mutex re-lock

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cpuset_mutex unlock and lock pair is only needed when transferring tasks
out of empty cpuset. Avoid unneeded cpuset_mutex re-lock when !is_empty
to save cpu cycles.

Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Miaohe Lin 2023-07-04 20:03:52 +08:00 committed by Tejun Heo
parent a453be9725
commit 48f074565b
1 changed files with 4 additions and 5 deletions
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9
kernel/cgroup/cpuset.c
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@ -3521,17 +3521,16 @@ hotplug_update_tasks_legacy(struct cpuset *cs,
is_empty = cpumask_empty(cs->cpus_allowed) ||
nodes_empty(cs->mems_allowed);
mutex_unlock(&cpuset_mutex);
/*
* Move tasks to the nearest ancestor with execution resources,
* This is full cgroup operation which will also call back into
* cpuset. Should be done outside any lock.
*/
if (is_empty)
if (is_empty) {
mutex_unlock(&cpuset_mutex);
remove_tasks_in_empty_cpuset(cs);
mutex_lock(&cpuset_mutex);
mutex_lock(&cpuset_mutex);
}
}
static void