Hi Jan, Thanks for your reply. On 19/8/15 23:13, Jan Kara wrote: > On Tue 30-07-19 09:34:39, Joseph Qi wrote: >> On 19/7/29 06:51, Dave Chinner wrote: >>> On Fri, Jul 26, 2019 at 09:12:07AM +0800, Joseph Qi 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? >>> >>> I suspect that the second part of this set of mods that Jan had >>> planned to do (on the write side to use shared locking as well) >>> did not happen and so the DIO writes are serialising the workload. >>> >> >> Thanks for the inputs, Dave. >> Hi Jan, Could you please confirm this? >> If so, should we revert this commit at present? > > Sorry for getting to you only now. I was on vacation and then catching up > with various stuff. I suppose you are not using dioread_nolock mount > option, are you? Can you check what are your results with that mount > option? > Yes, I've just used default mount options when testing. And it is indeed that there is performance improvement with dioread_nolock after reverting the 3 related commits. I'll do a supplementary test with parallel dio reads as well as dioread_nolock and send out the test result. > I have hard time remembering what I was thinking those couple years back > but I think the plan was to switch to dioread_nolock always but somehow I > didn't finish that and now I forgot where I got stuck because I don't see > any problem with that currently. Do you mean mark dioread_nolock as default? Thanks, Joseph > > Honza >
