On Mon, Jul 10, 2023 at 03:19:54PM +0200, Andreas Gruenbacher wrote: > Hi Wang Yugui, > > On Sun, May 28, 2023 at 5:53 PM Wang Yugui <wangyugui@xxxxxxxxxxxx> wrote: > > Hi, > > > > > Hi, > > > > > > gfs2 write bandwidth regression on 6.4-rc3 compare to 5.15.y. > > > > > > we added linux-xfs@ and linux-fsdevel@ because some related problem[1] > > > and related patches[2]. > > > > > > we compared 6.4-rc3(rather than 6.1.y) to 5.15.y because some related patches[2] > > > work only for 6.4 now. > > > > > > [1] https://lore.kernel.org/linux-xfs/20230508172406.1CF3.409509F4@xxxxxxxxxxxx/ > > > [2] https://lore.kernel.org/linux-xfs/20230520163603.1794256-1-willy@xxxxxxxxxxxxx/ > > > > > > > > > test case: > > > 1) PCIe3 SSD *4 with LVM > > > 2) gfs2 lock_nolock > > > gfs2 attr(T) GFS2_AF_ORLOV > > > # chattr +T /mnt/test > > > 3) fio > > > fio --name=global --rw=write -bs=1024Ki -size=32Gi -runtime=30 -iodepth 1 > > > -ioengine sync -zero_buffers=1 -direct=0 -end_fsync=1 -numjobs=1 \ > > > -name write-bandwidth-1 -filename=/mnt/test/sub1/1.txt \ > > > -name write-bandwidth-2 -filename=/mnt/test/sub2/1.txt \ > > > -name write-bandwidth-3 -filename=/mnt/test/sub3/1.txt \ > > > -name write-bandwidth-4 -filename=/mnt/test/sub4/1.txt > > > 4) patches[2] are applied to 6.4-rc3. > > > > > > > > > 5.15.y result > > > fio WRITE: bw=5139MiB/s (5389MB/s), > > > 6.4-rc3 result > > > fio WRITE: bw=2599MiB/s (2725MB/s) > > > > more test result: > > > > 5.17.0 WRITE: bw=4988MiB/s (5231MB/s) > > 5.18.0 WRITE: bw=5165MiB/s (5416MB/s) > > 5.19.0 WRITE: bw=5511MiB/s (5779MB/s) > > 6.0.5 WRITE: bw=3055MiB/s (3203MB/s), WRITE: bw=3225MiB/s (3382MB/s) > > 6.1.30 WRITE: bw=2579MiB/s (2705MB/s) > > > > so this regression happen in some code introduced in 6.0, > > and maybe some minor regression in 6.1 too? > > thanks for this bug report. Bob has noticed a similar looking > performance regression recently, and it turned out that commit > e1fa9ea85ce8 ("gfs2: Stop using glock holder auto-demotion for now") > inadvertently caused buffered writes to fall back to writing single > pages instead of multiple pages at once. That patch was added in > v5.18, so it doesn't perfectly align with the regression history > you're reporting, but maybe there's something else going on that we're > not aware of. Dave gave a good explanation of the problem here: https://lore.kernel.org/linux-xfs/ZKybxCxzmuI1TFYn@xxxxxxxxxxxxxxxxxxx/ It's a pagecache locking contention problem rather than an individual filesystem problem. ... are you interested in supporting large folios in gfs2? ;-)
