On 19/7/27 09:57, Andreas Dilger wrote: > It would be useful to post some details about your test hardware > (eg. HDD vs. SSD, CPU cores+speed, RAM), so that it is possible to make > a good comparison of someone sees different results. Sure, as I posted before, it is on Intel P3600 NVMe SSD. Other hardware information as below: CPU: Intel(R) Xeon(R) CPU E5-2682 v4 @ 2.50GHz * 64 MEM: 256G In fact, it behaves the same on different machines. So I think it has more to do with the test workload (concurrent rand read/write). Thanks, Joseph > > Cheers, Andreas > >> On Jul 25, 2019, at 19:12, Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> wrote: >> >> >> >>> On 19/7/26 05:20, Andreas Dilger wrote: >>> >>>> On Jul 23, 2019, at 5:17 AM, Joseph Qi <jiangqi903@xxxxxxxxx> wrote: >>>> >>>> Hi Ted & Jan, >>>> Could you please give your valuable comments? >>> >>> It seems like the original patches should be reverted? There is no data >> >> From my test result, yes. >> I've also tested libaio with iodepth 16, it behaves the same. Here is the test >> data for libaio 4k randrw: >> >> ------------------------------------------------------------------------------------------- >> w/ parallel dio reads | READ 78313KB/s, 19578, 1698.70us | WRITE 78313KB/s, 19578, 4837.60us >> ------------------------------------------------------------------------------------------- >> w/o parallel dio reads| READ 387774KB/s, 96943, 1009.73us | WRITE 387656KB/s，96914, 308.87us >> ------------------------------------------------------------------------------------------- >> >> Since this commit went into upstream long time ago，to be precise, Linux >> 4.9, I wonder if someone else has also observed this regression, or >> anything I missed? >> >> Thanks, >> Joseph >> >>> in the original commit message that indicates there is an actual performance >>> improvement from that patch, but there is data here showing it hurts both >>> read and write performance quite significantly. >>>> Cheers, Andreas >>> >>>>> On 19/7/19 17:22, Joseph Qi wrote: >>>>> Hi Ted & Jan, >>>>> I've observed an significant performance regression with the following >>>>> commit in my Intel P3600 NVMe SSD. >>>>> 16c54688592c ext4: Allow parallel DIO reads >>>>> >>>>> From my initial investigation, it may be because of the >>>>> inode_lock_shared (down_read) consumes more than inode_lock (down_write) >>>>> in mixed random read write workload. >>>>> >>>>> Here is my test result. >>>>> >>>>> ioengine=psync >>>>> direct=1 >>>>> rw=randrw >>>>> iodepth=1 >>>>> numjobs=8 >>>>> size=20G >>>>> runtime=600 >>>>> >>>>> w/ parallel dio reads : kernel 5.2.0 >>>>> w/o parallel dio reads: kernel 5.2.0, then revert the following commits: >>>>> 1d39834fba99 ext4: remove EXT4_STATE_DIOREAD_LOCK flag (related) >>>>> e5465795cac4 ext4: fix off-by-one error when writing back pages before dio read (related) >>>>> 16c54688592c ext4: Allow parallel DIO reads >>>>> >>>>> bs=4k: >>>>> ------------------------------------------------------------------------------------------- >>>>> w/ parallel dio reads | READ 30898KB/s, 7724, 555.00us | WRITE 30875KB/s, 7718, 479.70us >>>>> ------------------------------------------------------------------------------------------- >>>>> w/o parallel dio reads| READ 117915KB/s, 29478, 248.18us | WRITE 117854KB/s，29463, 21.91us >>>>> ------------------------------------------------------------------------------------------- >>>>> >>>>> bs=16k: >>>>> ------------------------------------------------------------------------------------------- >>>>> w/ parallel dio reads | READ 58961KB/s, 3685, 835.28us | WRITE 58877KB/s, 3679, 1335.98us >>>>> ------------------------------------------------------------------------------------------- >>>>> w/o parallel dio reads| READ 218409KB/s, 13650, 554.46us | WRITE 218257KB/s，13641, 29.22us >>>>> ------------------------------------------------------------------------------------------- >>>>> >>>>> bs=64k: >>>>> ------------------------------------------------------------------------------------------- >>>>> w/ parallel dio reads | READ 119396KB/s, 1865, 1759.38us | WRITE 119159KB/s, 1861, 2532.26us >>>>> ------------------------------------------------------------------------------------------- >>>>> w/o parallel dio reads| READ 422815KB/s, 6606, 1146.05us | WRITE 421619KB/s, 6587, 60.72us >>>>> ------------------------------------------------------------------------------------------- >>>>> >>>>> bs=512k: >>>>> ------------------------------------------------------------------------------------------- >>>>> w/ parallel dio reads | READ 392973KB/s, 767, 5046.35us | WRITE 393165KB/s, 767, 5359.86us >>>>> ------------------------------------------------------------------------------------------- >>>>> w/o parallel dio reads| READ 590266KB/s, 1152, 4312.01us | WRITE 590554KB/s, 1153, 2606.82us >>>>> ------------------------------------------------------------------------------------------- >>>>> >>>>> bs=1M: >>>>> ------------------------------------------------------------------------------------------- >>>>> w/ parallel dio reads | READ 487779KB/s, 476, 8058.55us | WRITE 485592KB/s, 474, 8630.51us >>>>> ------------------------------------------------------------------------------------------- >>>>> w/o parallel dio reads| READ 593927KB/s, 580, 7623.63us | WRITE 591265KB/s, 577, 6163.42us >>>>> ------------------------------------------------------------------------------------------- >>>>> >>>>> Thanks, >>>>> Joseph >>>>> >>> >>> >>> Cheers, Andreas >>> >>> >>> >>> >>>
