diff mbox series

[RFC,3/3] cgroup/cpuset: Iterate only if DEADLINE tasks are present

Message ID 20230315121812.206079-4-juri.lelli@redhat.com
State New
Headers
Series sched/deadline: cpuset: Rework DEADLINE bandwidth restoration |

Commit Message

Juri Lelli March 15, 2023, 12:18 p.m. UTC 
  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>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
---
 kernel/cgroup/cpuset.c | 3 +++
 1 file changed, 3 insertions(+)
diff mbox series

Patch

diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
index 57bc60112618..f46192d2e97e 100644
--- a/kernel/cgroup/cpuset.c
+++ b/kernel/cgroup/cpuset.c
@@ -1090,6 +1090,9 @@  static void 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)))