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@candle.pha.pa.us>
cc: pgsql-hackers@postgreSQL.org
Subject: Re: [HACKERS] Possible performance improvement: buffer replacement policy
In-reply-to: <200010161541.LAA06653@candle.pha.pa.us>
References: <200010161541.LAA06653@candle.pha.pa.us>
Comments: In-reply-to Bruce Momjian <pgman@candle.pha.pa.us>message dated "Mon, 16 Oct 2000 11:41:41 -0400"
Date: Mon, 16 Oct 2000 11:49:52 -0400
Message-ID: <26100.971711392@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>
X-Mailing-List: pgsql-hackers@postgresql.org
Precedence: bulk
Sender: pgsql-hackers-owner@hub.org
Status: RO
Content-Length: 947
Lines: 19
Bruce Momjian <pgman@candle.pha.pa.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