Re: Possible performance improvement: buffer replacement policy

I added this too to TODO.detail/performance.

> On Fri, Jan 19, 2001 at 12:03:58PM -0500, Bruce Momjian wrote:
> >
> > Tom, did we ever test this? I think we did and found that it was the
> > same or worse, right?
>
> (Funnily enough, I just read that message:)
>
> To: Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
> cc: pgsql-hackers(at)postgreSQL(dot)org
> Subject: Re: [HACKERS] Possible performance improvement: buffer replacement policy
> In-reply-to: <200010161541(dot)LAA06653(at)candle(dot)pha(dot)pa(dot)us>
> References: <200010161541(dot)LAA06653(at)candle(dot)pha(dot)pa(dot)us>
> Comments: In-reply-to Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>
> message dated "Mon, 16 Oct 2000 11:41:41 -0400"
> Date: Mon, 16 Oct 2000 11:49:52 -0400
> Message-ID: <26100(dot)971711392(at)sss(dot)pgh(dot)pa(dot)us>
> From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
> X-Mailing-List: pgsql-hackers(at)postgresql(dot)org
> Precedence: bulk
> Sender: pgsql-hackers-owner(at)hub(dot)org
> Status: RO
> Content-Length: 947
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>
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> >> It looks like it wouldn't take too much work to replace shared buffers
> >> on the basis of LRU-2 instead of LRU, so I'm thinking about trying it.
> >>
> >> Has anyone looked into this area? Is there a better method to try?
>
> > Sounds like a perfect idea. Good luck. :-)
>
> Actually, the idea went down in flames :-(, but I neglected to report
> back to pghackers about it. I did do some code to manage buffers as
> LRU-2. I didn't have any good performance test cases to try it with,
> but Richard Brosnahan was kind enough to re-run the TPC tests previously
> published by Great Bridge with that code in place. Wasn't any faster,
> in fact possibly a little slower, likely due to the extra CPU time spent
> on buffer freelist management. It's possible that other scenarios might
> show a better result, but right now I feel pretty discouraged about the
> LRU-2 idea and am not pursuing it.
>
> regards, tom lane
>
>

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