tree 7a649b1c8e4776ddbada58db00a69b56b9433942
parent 6b6ebb34744b21467aa01be7c53cc570fc41f70d
author Boris Burkov <boris@bur.io> 1590615799 -0700
committer Tejun Heo <tj@kernel.org> 1590674795 -0400

cgroup: add cpu.stat file to root cgroup

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>