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Re: More shared buffers causes lower performances

From: "Guillaume Smet" <guillaume(dot)smet(at)gmail(dot)com>
To: "Greg Smith" <gsmith(at)gregsmith(dot)com>
Cc: pgsql-performance <pgsql-performance(at)postgresql(dot)org>, "Stefan Kaltenbrunner" <stefan(at)kaltenbrunner(dot)cc>, Devrim GÜNDÜZ <devrim(at)commandprompt(dot)com>
Subject: Re: More shared buffers causes lower performances
Date: 2007-12-26 22:53:13
Message-ID: (view raw, whole thread or download thread mbox)
Lists: pgsql-performance
On Dec 26, 2007 10:52 PM, Guillaume Smet <guillaume(dot)smet(at)gmail(dot)com> wrote:
> Let's go with 8.2.5 on the same server (-s 100 / 16 clients / 50k
> transactions per client / only read using -S option):
> 64MB: 33814 tps
> 512MB: 35833 tps
> 1024MB: 36986 tps
> It's more consistent with what I expected.

I had the same numbers with 8.3b4.x86_64 RPMs compiled by Devrim than
with the ones I compiled myself. While discussing with Devrim, I
checked the .spec with a little more attention and... I noticed that
beta RPMs are by default compiled with --enable-debug and
--enable-cassert which doesn't help them to fly fast...
I did all my previous benchmarks with binaries compiled directly from
CVS so I didn't notice it before and this new server was far faster
than the box I tested 8.3devel before so I wasn't surprised by the
other results..

So, the conclusion is: if you really want to test/benchmark 8.3beta4
using the RPM packages, you'd better compile your own set of RPMs
using --define "beta 0".

Really sorry for the noise but anyway quite happy to have discovered
the pgbench-tools of Greg.

I hope it will be useful to other people. I'll post new results
yesterday with a clean beta4 install.


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