Re: Proposal for a regular upstream performance testing

[Stefan Hajnoczi]

On Mon, Mar 28, 2022 at 08:18:43AM +0200, Lukáš Doktor wrote:
> Hello Stefan, folks,
> 
> I seem to have another hit, an improvement actually and it seems to be 
> bisected all the way to you, Stefan. Let me use this as another example of 
> how such process could look like and we can use this to hammer-out the 
> details like via what means to submit the request, whom to notify and how to 
> proceed further.
> 
> ---
> 
> Last week I noticed an improvement in 
> TunedLibvirt/fio-rot-Aj-8i/0000:./write-4KiB/throughput/iops_sec.mean 
> (<driver name="qemu" type="raw" io="native" cache="none"/>, fio, rotationary 
> disk, raw file on host xfs partition, jobs=#cpus, iodepth=8, 4k writes) check 
> and bisected it to:
> 
> commit fc8796465c6cd4091efe6a2f8b353f07324f49c7
> Author: Stefan Hajnoczi <stefanha@redhat.com>
> Date:   Wed Feb 23 15:57:03 2022 +0000
> 
>     aio-posix: fix spurious ->poll_ready() callbacks in main loop
> 
> Could you please confirm that it does make sense and that it is expected? 
> (looks like it from the description).
> 
> Note that this commit was pin pointed using 2 out of 3 commits result, there 
> were actually some little differences between commits fc8 and cc5. The fc8 
> and 202 results scored similarly to both, good and bad commits with 2 being 
> closer to the bad one. Since cc5 they seem to stabilize further scoring 
> slightly lower than the median fc8 result. Anyway I don't have enough data to 
> declare anything. I can bisect it further if needed.

Yes, I can imagine that commit fc8796465c6c might improve non-IOThread
performance!

I don't know how to read the report:
- What is the difference between "Group stats" and "Failures"?
- Why are there 3 different means in "Group stats"?
- Why are there 3 "fc8" columns in "Failures"?

I don't feel confident searching git-log(1) output with 3-character
commit IDs. git itself uses 12 characters for short commit IDs with a
reasonably low chance of collisions.

Stefan

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