Re: Performance degradation in commit 6150a1b0

On Thu, Mar 31, 2016 at 01:10:56AM -0400, Noah Misch wrote:
> On Sun, Mar 27, 2016 at 02:15:50PM +0200, Andres Freund wrote:
> > On 2016-03-27 02:34:32 +0530, Ashutosh Sharma wrote:
> > > As mentioned in my earlier mail i was not able to apply
> > > *pinunpin-cas-5.patch* on commit *6150a1b0,
> >
> > That's not surprising; that's pretty old.
> >
> > > *therefore i thought of applying it on the latest commit and i was
> > > able to do it successfully. I have now taken the performance readings
> > > at latest commit i.e. *76281aa9* with and without applying
> > > *pinunpin-cas-5.patch* and my observations are as follows,
> > >
> >
> > > 1. I can still see that the current performance lags by 2-3% from the
> > > expected performance when *pinunpin-cas-5.patch *is applied on the commit
> > >
> > > *76281aa9.*
> > > 2. When *pinunpin-cas-5.patch *is ignored and performance is measured at
> > > commit *76281aa9 *the overall performance lags by 50-60% from the expected
> > > performance.
> > >
> > > *Note:* Here, the expected performance is the performance observed before
> > > commit *6150a1b0 *when* ac1d794 *is reverted.
> >
> > Thanks for doing these benchmarks. What's the performance if you revert
> > 6150a1b0 on top of a recent master? There've been a lot of other patches
> > influencing performance since 6150a1b0, so minor performance differences
> > aren't necessarily meaningful; especially when that older version then
> > had other patches reverted.
>
> [This is a generic notification.]
>
> The above-described topic is currently a PostgreSQL 9.6 open item. Andres,
> since you committed the patch believed to have created it, you own this open
> item. If that responsibility lies elsewhere, please let us know whose
> responsibility it is to fix this. Since new open items may be discovered at
> any time and I want to plan to have them all fixed well in advance of the ship
> date, I will appreciate your efforts toward speedy resolution. Please
> present, within 72 hours, a plan to fix the defect within seven days of this
> message. Thanks.

My attribution above was incorrect. Robert Haas is the committer and owner of
this one. I apologize.