Messages in this thread | | | Subject | Re: [PATCH -next 0/3] md/raid10: reduce lock contention for io | From | Yu Kuai <> | Date | Wed, 31 Aug 2022 20:07:15 +0800 |
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Hi, Paul!
在 2022/08/31 19:59, Paul Menzel 写道: > Dear Yu, > > > Am 30.08.22 um 03:09 schrieb Yu Kuai: > >> 在 2022/08/29 21:58, Paul Menzel 写道: > >>> Am 29.08.22 um 15:14 schrieb Yu Kuai: >>>> From: Yu Kuai <yukuai3@huawei.com> >>>> >>>> patch 1 is a small problem found by code review. >>>> patch 2 avoid holding resync_lock in fast path. >>>> patch 3 avoid holding lock in wake_up() in fast path. >>>> >>>> Test environment: >>>> >>>> Architecture: aarch64 >>>> Cpu: Huawei KUNPENG 920, there are four numa nodes >>>> >>>> Raid10 initialize: >>>> mdadm --create /dev/md0 --level 10 --bitmap none --raid-devices 4 >>>> /dev/nvme0n1 /dev/nvme1n1 /dev/nvme2n1 /dev/nvme3n1 >>>> >>>> Test cmd: >>>> fio -name=0 -ioengine=libaio -direct=1 -group_reporting=1 >>>> -randseed=2022 -rwmixread=70 -refill_buffers -filename=/dev/md0 >>>> -numjobs=16 -runtime=60s -bs=4k -iodepth=256 -rw=randread >>>> >>>> Test result: >>>> before this patchset: 2.9 GiB/s >>>> after this patchset: 6.6 Gib/s >>> >>> Could you please give more details about the test setup, like the >>> drives used? >> >> test setup is described above, four nvme disks is used. > > I was wondering about the model to be able to reproduce it. > >>> Did you use some tools like ftrace to figure out the bottleneck? >> >> Yes, I'm sure the bottleneck is spin_lock(), specifically threads from >> multiple nodes try to grab the same lock. By the way, if I bind the >> threads to the same node, performance can also improve to 6.6 Gib/s >> without this patchset. > > Interesting. Maybe you could add all that to the commit message of the > second patch.
Of course, I will do that in next version.
Thanks, Kuai > > > Kind regards, > > Paul > > >>>> Please noted that in kunpeng-920, memory access latency is very bad >>>> accross nodes compare to local node, and in other architecture >>>> performance improvement might not be significant. >>>> >>>> Yu Kuai (3): >>>> md/raid10: fix improper BUG_ON() in raise_barrier() >>>> md/raid10: convert resync_lock to use seqlock >>>> md/raid10: prevent unnecessary calls to wake_up() in fast path >>>> >>>> drivers/md/raid10.c | 88 >>>> +++++++++++++++++++++++++++++---------------- >>>> drivers/md/raid10.h | 2 +- >>>> 2 files changed, 59 insertions(+), 31 deletions(-) > . >
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