[PATCH 1/1] mm: change per-VMA lock statistics to be disabled by default

Suren Baghdasaryan
2023-04-28T17:35:40Z

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.

Fixes: 52f238653e45 ("mm: introduce per-VMA lock statistics")
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
mm/Kconfig.debug | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 6dae63b46368..a925415b4d10 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -274,6 +274,12 @@ config DEBUG_KMEMLEAK_AUTO_SCAN
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.
--
2.40.1.495.gc816e09b53d-goog