From: Shakeel Butt <shakeelb@google.com>
To: Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Muchun Song <songmuchun@bytedance.com>
Cc: "Michal Koutný" <mkoutny@suse.com>,
"Eric Dumazet" <edumazet@google.com>,
"Soheil Hassas Yeganeh" <soheil@google.com>,
"Feng Tang" <feng.tang@intel.com>,
"Oliver Sang" <oliver.sang@intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
lkp@lists.01.org, cgroups@vger.kernel.org, linux-mm@kvack.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
"Shakeel Butt" <shakeelb@google.com>
Subject: [PATCH v2 0/3] memcg: optimize charge codepath
Date: Thu, 25 Aug 2022 00:05:03 +0000 [thread overview]
Message-ID: <20220825000506.239406-1-shakeelb@google.com> (raw)
Recently Linux networking stack has moved from a very old per socket
pre-charge caching to per-cpu caching to avoid pre-charge fragmentation
and unwarranted OOMs. One impact of this change is that for network
traffic workloads, memcg charging codepath can become a bottleneck. The
kernel test robot has also reported this regression[1]. This patch
series tries to improve the memcg charging for such workloads.
This patch series implement three optimizations:
(A) Reduce atomic ops in page counter update path.
(B) Change layout of struct page_counter to eliminate false sharing
between usage and high.
(C) Increase the memcg charge batch to 64.
To evaluate the impact of these optimizations, on a 72 CPUs machine, we
ran the following workload in root memcg and then compared with scenario
where the workload is run in a three level of cgroup hierarchy with top
level having min and low setup appropriately.
$ netserver -6
# 36 instances of netperf with following params
$ netperf -6 -H ::1 -l 60 -t TCP_SENDFILE -- -m 10K
Results (average throughput of netperf):
1. root memcg 21694.8 Mbps
2. 6.0-rc1 10482.7 Mbps (-51.6%)
3. 6.0-rc1 + (A) 14542.5 Mbps (-32.9%)
4. 6.0-rc1 + (B) 12413.7 Mbps (-42.7%)
5. 6.0-rc1 + (C) 17063.7 Mbps (-21.3%)
6. 6.0-rc1 + (A+B+C) 20120.3 Mbps (-7.2%)
With all three optimizations, the memcg overhead of this workload has
been reduced from 51.6% to just 7.2%.
[1] https://lore.kernel.org/linux-mm/20220619150456.GB34471@xsang-OptiPlex-9020/
Changes since v1:
- Commit message updates
- Instead of explicit padding add align compiler option with struct
Shakeel Butt (3):
mm: page_counter: remove unneeded atomic ops for low/min
mm: page_counter: rearrange struct page_counter fields
memcg: increase MEMCG_CHARGE_BATCH to 64
include/linux/memcontrol.h | 7 ++++---
include/linux/page_counter.h | 34 +++++++++++++++++++++++-----------
mm/page_counter.c | 13 ++++++-------
3 files changed, 33 insertions(+), 21 deletions(-)
--
2.37.1.595.g718a3a8f04-goog
next reply other threads:[~2022-08-25 0:05 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-25 0:05 Shakeel Butt [this message]
2022-08-25 0:05 ` [PATCH v2 1/3] mm: page_counter: remove unneeded atomic ops for low/min Shakeel Butt
2022-08-25 6:43 ` Michal Hocko
2022-08-25 0:05 ` [PATCH v2 2/3] mm: page_counter: rearrange struct page_counter fields Shakeel Butt
2022-08-25 0:33 ` Andrew Morton
2022-08-25 4:41 ` Shakeel Butt
2022-08-25 5:21 ` Andrew Morton
2022-08-25 15:24 ` Shakeel Butt
2022-08-25 6:47 ` Michal Hocko
2022-08-25 15:25 ` Shakeel Butt
2022-08-25 0:05 ` [PATCH v2 3/3] memcg: increase MEMCG_CHARGE_BATCH to 64 Shakeel Butt
2022-08-25 6:49 ` Michal Hocko
2022-08-25 8:30 ` Muchun Song
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