Re: Performance improvement with 6d740fb01b9f0f5ea7a82f4d5e458d91940a19ee

[Stefan Hajnoczi <stefanha@gmail.com>]

On Fri, 26 May 2023 at 04:07, Lukáš Doktor <ldoktor@redhat.com> wrote:
>
> Dne 25. 05. 23 v 17:21 Stefan Hajnoczi napsal(a):
> > On Thu, 25 May 2023 at 06:18, Lukáš Doktor <ldoktor@redhat.com> wrote:
> >> the perf-ci detected and bisected the 6d740fb - aio-posix: do not nest poll handlers - as a performance improvement when using multiple concurrent jobs and 4k (22%) as well as 1024k (63%) blocks on aarch64 (on a slow rotational disk).
> >>
> >>     https://ldoktor.github.io/tmp/RedHat-virtlab-arm09/v8.0.0/150-improvement.html
> >>
> >> Based on the commit message I guess it's expected so take this just as a record of an improvement.
> >
> > The commit was not intended to change performance and I'm not sure why
> > it happens!
> >
>
> It had and today the x86_64 pipeline finished which shows similar improvement just not in read but rather in write instead and only for 4k blocks (~40%). For 1024k blocks I can see it scoring a bit better (~1.5%). Reads are too jittery to really tell anything on that machine. Anyway I have not done any thorough testing, just a bisection with the most significant setting.
>
> From around the same time I can see a NVMe regression in 4k writes, but first bisection job showed nothing. I'll increase the range and try again as each job since that day shows similar drop.

Thanks!

Stefan