cgroup: add cpu.stat file to root cgroup

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Currently, the root cgroup does not have a cpu.stat file. Add one which
is consistent with /proc/stat to capture global cpu statistics that
might not fall under cgroup accounting.

We haven't done this in the past because the data are already presented
in /proc/stat and we didn't want to add overhead from collecting root
cgroup stats when cgroups are configured, but no cgroups have been
created.

By keeping the data consistent with /proc/stat, I think we avoid the
first problem, while improving the usability of cgroups stats.
We avoid the second problem by computing the contents of cpu.stat from
existing data collected for /proc/stat anyway.

Signed-off-by: Boris Burkov <boris@bur.io>
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

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Boris Burkov 2020-05-27 14:43:19 -07:00 • committed by Tejun Heo

parent 6b6ebb3474

commit 936f2a70f2

3 changed files with 54 additions and 13 deletions

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6

Documentation/admin-guide/cgroup-v2.rst

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1

kernel/cgroup/cgroup.c

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58

kernel/cgroup/rstat.c

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