On 7/4/23 08:03, Miaohe Lin wrote:
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@xxxxxxxxxx>
---
kernel/cgroup/cpuset.c | 9 ++++-----
1 file changed, 4 insertions(+), 5 deletions(-)
diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 601c40da8e03..e136269c152c 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -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
Reviewed-by: Waiman Long <longman@xxxxxxxxxx>
