From 71cf567de1ff39abc57db7b07bbac961398ca237 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Mon, 8 May 2023 09:58:52 +0200 Subject: [PATCH] FROMGIT: 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. Bug: 238390134 Reported-by: Qais Yousef Link: https://lore.kernel.org/lkml/20230206221428.2125324-1-qyousef@layalina.io/ Signed-off-by: Juri Lelli Reviewed-by: Waiman Long Signed-off-by: Tejun Heo (cherry picked from commit c0f78fd5edcf29b2822ac165f9248a6c165e8554 https://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git cgroup/for-6.5) Signed-off-by: Qais Yousef Change-Id: Idc3f348d90b1024be2408fe8a855e09c354409c8 --- kernel/cgroup/cpuset.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c index 3176fd2e3905..5e2b0b996d27 100644 --- a/kernel/cgroup/cpuset.c +++ b/kernel/cgroup/cpuset.c @@ -978,6 +978,9 @@ 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)))