PSI accounts stalls for each cgroup separately and aggregates it at each
level of the hierarchy. This causes additional overhead with psi_avgs_work
being called for each cgroup in the hierarchy. psi_avgs_work has been
highly optimized, however on systems with large number of cgroups the
overhead becomes noticeable.
Systems which use PSI only at the system level could avoid this overhead
if PSI can be configured to skip per-cgroup stall accounting.
Add "cgroup_disable=pressure" kernel command-line option to allow
requesting system-wide only pressure stall accounting. When set, it
keeps system-wide accounting under /proc/pressure/ but skips accounting
for individual cgroups and does not expose PSI nodes in cgroup hierarchy.
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/patchwork/patch/1435705
(cherry picked from commit 3958e2d0c34e18c41b60dc01832bd670a59ef70f
https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git tj)
Conflicts:
include/linux/cgroup-defs.h
kernel/cgroup/cgroup.c
1. Trivial merge conflict in cgroup-defs.h due to missing CFTYPE_DEBUG
2. Changed flags to (CFTYPE_NOT_ON_ROOT | CFTYPE_PRESSURE) in cgroup.c
because in 4.19 psi files were allowed only in non-root cgroups.
Bug: 178872719
Bug: 191734423
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: Ifc8fbc52f9a1131d7c2668edbb44c525c76c3360
Git-commit: 92c6dd6a650e1c9161b3e9b37cb7e34b98c32b06
Git-repo: https://android.googlesource.com/kernel/common/
Signed-off-by: Srinivasarao P <spathi@codeaurora.org>
f7c2472acb