Documentation/admin-guide/cgroup-v2.rst: document why inactive_X + active_X may not equal X

This has confused a significant number of people using cgroups inside
Facebook, and some of those outside as well judging by posts like
this[0] (although it's not a problem unique to cgroup v2).

If shmem handling in particular becomes more coherent at some point in
the future -- although that seems unlikely now -- we can change the
wording here.

[0]: https://unix.stackexchange.com/q/525092/10762

Link: http://lkml.kernel.org/r/20191111144958.GA11914@chrisdown.name
Signed-off-by: Chris Down <chris@chrisdown.name>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Roman Gushchin <guro@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Chris Down 2019-11-30 17:50:19 -08:00 committed by Linus Torvalds
parent fa40d1ee9f
commit 1603c8d1b1

View File

@ -1288,7 +1288,12 @@ PAGE_SIZE multiple when read back.
inactive_anon, active_anon, inactive_file, active_file, unevictable
Amount of memory, swap-backed and filesystem-backed,
on the internal memory management lists used by the
page reclaim algorithm
page reclaim algorithm.
As these represent internal list state (eg. shmem pages are on anon
memory management lists), inactive_foo + active_foo may not be equal to
the value for the foo counter, since the foo counter is type-based, not
list-based.
slab_reclaimable
Part of "slab" that might be reclaimed, such as