tree 208946c2b33e3eeaa8e7f7d0eedc0a9c0401b4bd
parent 1f7dd3e5a6e4f093017fff12232572ee1aa4639b
author Tejun Heo <tj@kernel.org> 1449155901 -0500
committer Tejun Heo <tj@kernel.org> 1449155901 -0500

cgroup_pids: don't account for the root cgroup

Because accounting resources for the root cgroup sometimes incurs
measureable overhead for workloads which don't care about cgroup and
often ends up calculating a number which is available elsewhere in a
slightly different form, cgroup is not in the business of providing
system-wide statistics.  The pids controller which was introduced
recently was exposing "pids.current" at the root.  This patch disable
accounting for root cgroup and removes the file from the root
directory.

While this is a userland visible behavior change, pids has been
available only in one version and was badly broken there, so I don't
think this will be noticeable.  If it turns out to be a problem, we
can reinstate it for v1 hierarchies.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Aleksa Sarai <cyphar@cyphar.com>