Hi,
On 2022-09-22 16:07:02 -0500, Justin Pryzby wrote:
> On Sun, Aug 28, 2022 at 02:28:02PM -0700, Andres Freund wrote:
> > > > > @@ -71,8 +69,6 @@ task:
> > > > > fingerprint_key: ccache/freebsd
> > > > > reupload_on_changes: true
> > > > >
> > > > > - # Workaround around performance issues due to 32KB block size
> > > > > - repartition_script: src/tools/ci/gcp_freebsd_repartition.sh
> > > > > create_user_script: |
> > > > > pw useradd postgres
> > > > > chown -R postgres:postgres .
> > > > > --
> > > >
> > > > What's the story there - at some point that was important for performance
> > > > because of the native block size triggering significant read-modify-write
> > > > cycles with postres' writes. You didn't comment on it in the commit message.
> > >
> > > Well, I don't know the history, but it seems to be unneeded now.
> >
> > It's possible it was mainly needed for testing with aio + dio. But also
> > possible that an upgrade improved the situation since.
>
> Maybe freebsd got faster as a result of the TAU CPUs?
> https://mobile.twitter.com/cirrus_labs/status/1534982111568052240
>
> I noticed because it's been *slower* the last ~24h since cirrusci
> disabled TAU, as Thomas commit mentioned.
> https://twitter.com/cirrus_labs/status/1572657320093712384
Yea, I noticed that as well. It's entirely possible that something in the
"hardware" stack improved sufficiently to avoid problems.
> I have no idea if the TAU CPUs eliminate/mitigate the original
> performance issue you had with AIO. But they have such a large effect
> on freebsd that it could now be the fastest task, if given more than 2
> CPUs.
I'm planning to rebase early next week and try that out.
Greetings,
Andres Freund
