* [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock
@ 2023-07-04 12:03 Miaohe Lin
2023-07-05 3:10 ` Waiman Long
2023-07-10 20:26 ` Tejun Heo
0 siblings, 2 replies; 3+ messages in thread
From: Miaohe Lin @ 2023-07-04 12:03 UTC (permalink / raw)
To: longman, tj, hannes, lizefan.x; +Cc: cgroups, linux-kernel, linmiaohe
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>
---
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
--
2.33.0
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock
2023-07-04 12:03 [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock Miaohe Lin
@ 2023-07-05 3:10 ` Waiman Long
2023-07-10 20:26 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Waiman Long @ 2023-07-05 3:10 UTC (permalink / raw)
To: Miaohe Lin, tj, hannes, lizefan.x; +Cc: cgroups, linux-kernel
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@huawei.com>
> ---
> 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@redhat.com>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock
2023-07-04 12:03 [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock Miaohe Lin
2023-07-05 3:10 ` Waiman Long
@ 2023-07-10 20:26 ` Tejun Heo
1 sibling, 0 replies; 3+ messages in thread
From: Tejun Heo @ 2023-07-10 20:26 UTC (permalink / raw)
To: Miaohe Lin; +Cc: longman, hannes, lizefan.x, cgroups, linux-kernel
On Tue, Jul 04, 2023 at 08:03:52PM +0800, 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@huawei.com>
Applied to cgroup/for-6.6.
Thanks.
--
tejun
^ permalink raw reply [flat|nested] 3+ messages in thread
end of thread, other threads:[~2023-07-10 20:26 UTC | newest]
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2023-07-04 12:03 [PATCH] cgroup/cpuset: avoid unneeded cpuset_mutex re-lock Miaohe Lin
2023-07-05 3:10 ` Waiman Long
2023-07-10 20:26 ` Tejun Heo
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