Re: testing HS/SR - 1 vs 2 performance

On Fri, 2010-04-16 at 11:29 +0300, Heikki Linnakangas wrote:
> Simon Riggs wrote:
> > On Tue, 2010-04-13 at 21:09 +0300, Heikki Linnakangas wrote:
> >> A quick fix would be to check if there's any entries in the hash table
> >> before scanning it. That would eliminate the overhead when there's no
> >> in-progress transactions in the master. But as soon as there's even one,
> >> the overhead comes back.
> >
> > Any fix should be fairly quick because of the way its modularised - with
> > something like this in mind.
> >
> > I'll try a circular buffer implementation, with fastpath.
>
> I started experimenting with a sorted array based implementation on
> Tuesday but got carried away with other stuff. I now got back to that
> and cleaned it up.
>
> How does the attached patch look like? It's probably similar to what you
> had in mind.

It looks like a second version of what I'm working on and about to
publish. I'll take that as a compliment!

My patch is attached here also, for discussion.

The two patches look same in their main parts, though I have quite a few
extra tweaks in there, which you can read about in comments. One tweak I
don't have is the use of the presence array that allows a sensible
bsearch, so I'll to alter my patch to use that idea but keep the rest of
my code.

--
Simon Riggs www.2ndQuadrant.com