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? 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. Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR
