From 48f074565bb7eaa9ae502b2b2d423b1e50325e1b Mon Sep 17 00:00:00 2001 From: Miaohe Lin Date: Tue, 4 Jul 2023 20:03:52 +0800 Subject: [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock 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 Reviewed-by: Waiman Long Signed-off-by: Tejun Heo --- 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