commit d4a5b369ad upstream.
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 f82e6bf9bb ("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@google.com
Fixes: f82e6bf9bb ("mm: memcg: use rstat for non-hierarchical stats")
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jesper Dangaard Brouer <hawk@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use make htmldocs or
make pdfdocs. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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