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
