On 19/9/18 18:03, Ritesh Harjani wrote: > Hello Joseph, > > First of all thanks a lot for collecting a thorough > performance numbers. > > On 9/18/19 12:05 PM, Joseph Qi wrote: >> Hi Ritesh, >> >> On 19/9/17 18:32, Ritesh Harjani wrote: >>> Hello, >>> >>> This patch series is based on the upstream discussion with Jan >>> & Joseph @ [1]. >>> It is based on top of Matthew's v3 ext4 iomap patch series [2] >>> >>> Patch-1: Adds the ext4_ilock/unlock APIs and also replaces all >>> inode_lock/unlock instances from fs/ext4/* >>> >>> For now I already accounted for trylock/lock issue symantics >>> (which was discussed here [3]) in the same patch, >>> since the this whole patch was around inode_lock/unlock API, >>> so I thought it will be best to address that issue in the same patch. >>> However, kindly let me know if otherwise. >>> >>> Patch-2: Commit msg of this patch describes in detail about >>> what it is doing. >>> In brief - we try to first take the shared lock (instead of exclusive >>> lock), unless it is a unaligned_io or extend_io. Then in >>> ext4_dio_write_checks(), if we start with shared lock, we see >>> if we can really continue with shared lock or not. If not, then >>> we release the shared lock then acquire exclusive lock >>> and restart ext4_dio_write_checks(). >>> >>> >>> Tested against few xfstests (with dioread_nolock mount option), >>> those ran fine (ext4 & generic). >>> >>> I tried testing performance numbers on my VM (since I could not get >>> hold of any real h/w based test device). I could test the fact >>> that earlier we were trying to do downgrade_write() lock, but with >>> this patch, that path is now avoided for fio test case >>> (as reported by Joseph in [4]). >>> But for the actual results, I am not sure if VM machine testing could >>> really give the reliable perf numbers which we want to take a look at. >>> Though I do observe some form of perf improvements, but I could not >>> get any reliable numbers (not even with the same list of with/without >>> patches with which Joseph posted his numbers [1]). >>> >>> >>> @Joseph, >>> Would it be possible for you to give your test case a run with this >>> patches? That will be really helpful. >>> >>> Branch for this is hosted at below tree. >>> >>> https://github.com/riteshharjani/linux/tree/ext4-ilock-RFC >>> >> I've tested your branch, the result is: >> mounting with dioread_nolock, it behaves the same like reverting >> parallel dio reads + dioread_nolock; > > Good sign, means that patch is doing what it is supposed to do. > > >> while mounting without dioread_nolock, no improvement, or even worse. >> Please refer the test data below. > Actually without dioread_nolock, we take the restart path. > i.e. initially we start with SHARED_LOCK, but if dioread_nolock > is not enabled (or check some other conditions like overwrite), > we release the shared lock and re-acquire the EXCL lock. > > > But as an optimization, I added the below diff just now > to directly first check for ext4_should_dioread_nolock too > before taking the shared lock. > > I think with this we should not see any performance regression > (even without dioread_nolock mount option). > Since it will directly start with exclusive lock > if dioread_nolock mount option is not enabled. > > I have updated the tree with this diff in same branch. > > > ext4_dio_file_write_iter () > <...> > > 498 if (iolock == EXT4_IOLOCK_SHARED && !ext4_should_dioread_nolock(inode)) > 499 iolock = EXT4_IOLOCK_EXCL; > 500 > <...> > > >> >> fio -name=parallel_dio_reads_test -filename=/mnt/nvme0n1/testfile >> -direct=1 -iodepth=1 -thread -rw=randrw -ioengine=psync -bs=$bs >> -size=20G -numjobs=8 -runtime=600 -group_reporting >> >> w/ = with parallel dio reads >> w/o = reverting parallel dio reads >> w/o+ = reverting parallel dio reads + dioread_nolock >> ilock = ext4-ilock-RFC >> ilock+ = ext4-ilock-RFC + dioread_nolock > > I will request to kindly also add "w/ + dioread_nolock" in your list. > I've done this test before, it still behaves poor. You can refer the previous RFC thread: https://www.spinics.net/lists/linux-ext4/msg67066.html Thanks, Joseph > > "w/ + dioread_nolock" v/s "ilock+" - should show some improvements. > "w/ " v/s "ilock" - should not show any regression. > > But thanks for the exhaustive performance numbers you collected. > > > -ritesh > > >> >> bs=4k: >> -------------------------------------------------------------- >> | READ | WRITE | >> -------------------------------------------------------------- >> w/ | 30898KB/s,7724,555.00us | 30875KB/s,7718,479.70us | >> -------------------------------------------------------------- >> w/o | 117915KB/s,29478,248.18us | 117854KB/s,29463,21.91us | >> -------------------------------------------------------------- >> w/o+ | 123450KB/s,30862,245.77us | 123368KB/s,30841,12.14us | >> -------------------------------------------------------------- >> ilock | 29964KB/s,7491,326.70us | 29940KB/s,7485,740.62us | >> -------------------------------------------------------------- >> ilock+| 123685KB/s,30921,245.52us | 123601KB/s,30900,12.11us | >> -------------------------------------------------------------- >> >> >> bs=16k: >> -------------------------------------------------------------- >> | READ | WRITE | >> -------------------------------------------------------------- >> w/ | 58961KB/s,3685,835.28us | 58877KB/s,3679,1335.98us | >> -------------------------------------------------------------- >> w/o | 218409KB/s,13650,554.46us | 218257KB/s,13641,29.22us | >> -------------------------------------------------------------- >> w/o+ | 222477KB/s,13904,552.94us | 222322KB/s,13895,20.28us | >> -------------------------------------------------------------- >> ilock | 56039KB/s,3502,632.96us | 55943KB/s,3496,1652.72us | >> -------------------------------------------------------------- >> ilock+| 222747KB/s,13921,552.57us | 222592KB/s,13912,20.31us | >> -------------------------------------------------------------- >> >> bs=64k >> ---------------------------------------------------------------- >> | READ | WRITE | >> ---------------------------------------------------------------- >> w/ | 119396KB/s,1865,1759.38us | 119159KB/s,1861,2532.26us | >> ---------------------------------------------------------------- >> w/o | 422815KB/s,6606,1146.05us | 421619KB/s,6587,60.72us | >> --------------------------------------------,------------------- >> w/o+ | 427406KB/s,6678,1141.52us | 426197KB/s,6659,52.79us | >> ---------------------------------------------------------------- >> ilock | 105800KB/s,1653,1451.68us | 105721KB/s,1651,3388.64us | >> ---------------------------------------------------------------- >> ilock+| 427678KB/s,6682,1142.13us | 426468KB/s,6663,52.31us | >> ---------------------------------------------------------------- >> >> bs=512k >> ---------------------------------------------------------------- >> | READ | WRITE | >> ---------------------------------------------------------------- >> w/ | 392973KB/s,767,5046.35us | 393165KB/s,767,5359.86us | >> ---------------------------------------------------------------- >> w/o | 590266KB/s,1152,4312.01us | 590554KB/s,1153,2606.82us | >> ---------------------------------------------------------------- >> w/o+ | 618752KB/s,1208,4125.82us | 619054KB/s,1209,2487.90us | >> ---------------------------------------------------------------- >> ilock | 296239KB/s,578,4703.10us | 296384KB/s,578,9049.32us | >> ---------------------------------------------------------------- >> ilock+| 616636KB/s,1204,4143.38us | 616937KB/s,1204,2490.08us | >> ---------------------------------------------------------------- >> >> bs=1M >> ---------------------------------------------------------------- >> | READ | WRITE | >> ---------------------------------------------------------------- >> w/ | 487779KB/s,476,8058.55us | 485592KB/s,474,8630.51us | >> ---------------------------------------------------------------- >> w/o | 593927KB/s,580,7623.63us | 591265KB/s,577,6163.42us | >> ---------------------------------------------------------------- >> w/o+ | 615011KB/s,600,7399.93us | 612255KB/s,597,5936.61us | >> ---------------------------------------------------------------- >> ilock | 394762KB/s,385,7097.55us | 392993KB/s,383,13626.98us | >> ---------------------------------------------------------------- >> ilock+| 626183KB/s,611,7319.16us | 623377KB/s,608,5773.24us | >> ---------------------------------------------------------------- >> >> Thanks, >> Joseph >>
