tree ff0eb5de0eba86b8a55caaaa1288b0517fe2eb69
parent 9f130806127d10ace29196cd880855d34b01bfed
author Shakeel Butt <shakeelb@google.com> 1705088863 +0000
committer COS Cherry Picker <cloud-image-release@prod.google.com> 1705701569 -0800

mm: writeback: ratelimit stat flush from mem_cgroup_wb_stats

One of our workloads (Postgres 14) has regressed when migrated from 5.10
to 6.1 upstream kernel. The regression can be reproduced by sysbench's
oltp_write_only benchmark. It seems like the always on rstat flush in
mem_cgroup_wb_stats() is causing the regression. So, rate limit that
specific rstat flush. One potential consequence would be the dirty
throttling might be decided on stale memcg stats. However from our
benchmarks and production traffic we have not observed any change in the
dirty throttling behavior of the application.

Signed-off-by: Shakeel Butt <shakeelb@google.com>

BUG=b/246641795
TEST=presubmit
RELEASE_NOTE=Fixed a performance issue observed in Postgres databases.

cos-patch: bug
Change-Id: Ibc11a3db969b427fcac92a12d187c42f3410760b
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/63572
Reviewed-by: Oleksandr Tymoshenko <ovt@google.com>
Main-Branch-Verified: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
Reviewed-by: Robert Kolchmeyer <rkolchmeyer@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>