cgroup/cpu: document cpu.stat.local and clarify cpu.stat behavior

Add documentation for the cpu.stat.local interface file, which reports
the throttled_usec stat -- the actual throttling time incurred by the
cgroup's own runqueues, which may include throttling inherited from
ancestor cgroup bandwidth limits. Unlike cpu.stat's throttled_usec
which only accounts for throttling caused by the cgroup's own CFS
bandwidth limit.

When the controller is not enabled, the stat is not reported.

Also clarify cpu.stat descriptions: note that the three base CPU usage
stats (usage_usec, user_usec, system_usec) include descendant cgroups,
and that the five CFS bandwidth stats are non-hierarchical -- they only
account for throttling caused by the cgroup's own bandwidth limit.

Signed-off-by: Sun Shaojie <sunshaojie@kylinos.cn>
Acked-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This commit is contained in:
Sun Shaojie 2026-06-29 14:06:36 +08:00 • committed by Tejun Heo
commit 171569f8ee