On Fri 16-08-19 21:23:24, Joseph Qi wrote: > 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? Yes, in fact I'd like to just remove the other path so that we can remove this confusing mount option. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
