On 2022-04-21 02:45, Xiao Ni wrote: > Could you share the commands to get the test result (lock contention > and performance)? Sure. The performance we were focused on was large block writes. So we setup raid5 instances with varying number of disks and ran the following fio script directly on the drive. [simple] filename=/dev/md0 ioengine=libaio rw=write direct=1 size=8G blocksize=2m iodepth=16 runtime=30s time_based=1 offset_increment=8G numjobs=12  (We also played around with tuning this but didn't find substantial changes once the bottleneck was hit) We tuned md with parameters like: echo 4 > /sys/block/md0/md/group_thread_cnt echo 8192 > /sys/block/md0/md/stripe_cache_size For lock contention stats, we just used lockstat[1]; roughly like: echo 1 > /proc/sys/kernel/lock_stat fio test.fio echo 0 > /proc/sys/kernel/lock_stat cat /proc/lock_stat And compared the before and after. Logan [1] https://www.kernel.org/doc/html/latest/locking/lockstat.html
