UPSTREAM: mm: change per-VMA lock statistics to be disabled by default

Change CONFIG_PER_VMA_LOCK_STATS to be disabled by default, as most users
don't need it.  Add configuration help to clarify its usage.

Link: https://lkml.kernel.org/r/20230428173533.18158-1-surenb@google.com
Fixes: 52f238653e45 ("mm: introduce per-VMA lock statistics")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

(cherry picked from commit 6152e53d9671b0ccc21c1bca842617b32ccfc5d8)

Bug: 161210518
Change-Id: Ibd57999a415b5433ae3b99365ea50526a35452d1
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
This commit is contained in:
Suren Baghdasaryan 2023-04-28 10:35:33 -07:00 committed by Carlos Llamas
parent bfef68d9a6
commit 78c6875e2f

View file

@ -227,6 +227,12 @@ config PTDUMP_DEBUGFS
config PER_VMA_LOCK_STATS
bool "Statistics for per-vma locks"
depends on PER_VMA_LOCK
default y
help
Statistics for per-vma locks.
Say Y here to enable success, retry and failure counters of page
faults handled under protection of per-vma locks. When enabled, the
counters are exposed in /proc/vmstat. This information is useful for
kernel developers to evaluate effectiveness of per-vma locks and to
identify pathological cases. Counting these events introduces a small
overhead in the page fault path.
If in doubt, say N.