cgroup/cpuset: Iterate only if DEADLINE tasks are present

update_tasks_root_domain currently iterates over all tasks even if no
DEADLINE task is present on the cpuset/root domain for which bandwidth
accounting is being rebuilt. This has been reported to introduce 10+ ms
delays on suspend-resume operations.

Skip the costly iteration for cpusets that don't contain DEADLINE tasks.

Reported-by: Qais Yousef <qyousef@layalina.io>
Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Juri Lelli 2023-05-08 09:58:52 +02:00 committed by Tejun Heo
parent 6c24849f55
commit c0f78fd5ed

View File

@ -1092,6 +1092,9 @@ static void dl_update_tasks_root_domain(struct cpuset *cs)
struct css_task_iter it;
struct task_struct *task;
if (cs->nr_deadline_tasks == 0)
return;
css_task_iter_start(&cs->css, 0, &it);
while ((task = css_task_iter_next(&it)))