The patch titled
Subject: mm: ratelimit stat flush from workingset shrinker
has been added to the -mm mm-unstable branch. Its filename is
mm-ratelimit-stat-flush-from-workingset-shrinker.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-ratelimit-stat-flush-from-workingset-shrinker.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: mm: ratelimit stat flush from workingset shrinker
Date: Thu, 28 Dec 2023 07:30:55 +0000
One of our workloads (Postgres 14 + sysbench OLTP) regressed on newer
upstream kernel and on further investigation, it seems like the cause is
the always synchronous rstat flush in the count_shadow_nodes() added by
the commit f82e6bf9bb9b ("mm: memcg: use rstat for non-hierarchical
stats"). On further inspection it seems like we don't really need
accurate stats in this function as it was already approximating the amount
of appropriate shadow entries to keep for maintaining the refault
information. Since there is already 2 sec periodic rstat flush, we don't
need exact stats here. Let's ratelimit the rstat flush in this code path.
Link: https://lkml.kernel.org/r/20231228073055.4046430-1-shakeelb@xxxxxxxxxx
Fixes: f82e6bf9bb9b ("mm: memcg: use rstat for non-hierarchical stats")
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/workingset.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/workingset.c~mm-ratelimit-stat-flush-from-workingset-shrinker
+++ a/mm/workingset.c
@@ -680,7 +680,7 @@ static unsigned long count_shadow_nodes(
struct lruvec *lruvec;
int i;
- mem_cgroup_flush_stats(sc->memcg);
+ mem_cgroup_flush_stats_ratelimited(sc->memcg);
lruvec = mem_cgroup_lruvec(sc->memcg, NODE_DATA(sc->nid));
for (pages = 0, i = 0; i < NR_LRU_LISTS; i++)
pages += lruvec_page_state_local(lruvec,
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
mm-ratelimit-stat-flush-from-workingset-shrinker.patch
