From:   Shaoying Xu <shaoyi@amazon.com>
To:     <stable@vger.kernel.org>
CC:     <abuehaze@amazon.com>, <peterz@infradead.org>,
        <longman@redhat.com>, Shaoying Xu <shaoyi@amazon.com>
Subject: [PATCH stable 5.10 0/7] Remove reader optimistic spinning
Date:   Tue, 7 Feb 2023 19:01:28 +0000
Message-ID: <20230207190135.25258-1-shaoyi@amazon.com>
MIME-Version: 1.0
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This patch series is to remove reader optimistic spinning in
kernel 5.10 to improve the MongoDB performance. Performance measurements
(10 times running average of overall throughput ops/sec) are using
MongoDB 5.0.11 and YCSB [1] microbenchmark with workloadA [2] on AWS EC2
m5.4xlarge/m6g.4xlarge (16-vCPU 64GiB-memory) instances with a 512GB EBS
IO1 drive disk with 5000 IOPS and separating MongoDB and YCSB load generator
on 2 instances and setting recordcount=25000000 and operationcount=10000000
to see the impacts of these changes:

  Before - v5.10.165 kernel in OS Amazon Linux 2
  After  - v5.10.165 kernel with reader spinning disabled in OS Amazon Linux 2

  | Arch    | Instance Type | Before  | After   |
  |---------+---------------+---------+---------|
  | x86_64  | m5.4xlarge    | 37365.4 | 42373.9 |
  |---------+---------------+---------+---------|
  | aarch64 | m6g.4xlarge   | 33823.1 | 43113.7 |
  |---------+---------------+---------+---------|

It can be seen that the MongoDB throughput can be improved around 13% in x86_64
and 27% in aarch64 after disabling reader optimistic spinning and these patches 
can be applied to 5.10 with no conflict so we wonder if it's possible to backport 
them to stable 5.10? 

[1] https://github.com/brianfrankcooper/YCSB/releases/download/0.17.0/ycsb-0.17.0.tar.gz
[2] https://github.com/brianfrankcooper/YCSB/blob/master/workloads/workloada

Thanks,
Shaoying

Peter Zijlstra (3):
  locking/rwsem: Better collate rwsem_read_trylock()
  locking/rwsem: Introduce rwsem_write_trylock()
  locking/rwsem: Fold __down_{read,write}*()

Waiman Long (4):
  locking/rwsem: Pass the current atomic count to
    rwsem_down_read_slowpath()
  locking/rwsem: Prevent potential lock starvation
  locking/rwsem: Enable reader optimistic lock stealing
  locking/rwsem: Remove reader optimistic spinning

 kernel/locking/lock_events_list.h |   6 +-
 kernel/locking/rwsem.c            | 359 +++++++++---------------------
 2 files changed, 106 insertions(+), 259 deletions(-)

-- 
2.38.1