From: Kenneth Marshall <ktm@it.is.rice.edu>
To: Guillaume Smet <guillaume.smet@gmail.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: PostgreSQL and Xeon MP
Date: Thu, 16 Mar 2006 08:30:20 -0600
Message-ID: <20060316143020.GW22830@it.is.rice.edu> (raw)
In-Reply-To: <1d4e0c10603160245n55128e86t35431a339afcf8cc@mail.gmail.com>
References: <1d4e0c10603160245n55128e86t35431a339afcf8cc@mail.gmail.com>
On Thu, Mar 16, 2006 at 11:45:12AM +0100, Guillaume Smet wrote:
> Hello,
>
> We are experiencing performances problem with a quad Xeon MP and
> PostgreSQL 7.4 for a year now. Our context switch rate is not so high
> but the load of the server is blocked to 4 even on very high load and
> we have 60% cpu idle even in this case. Our database fits in RAM and
> we don't have any IO problem. I saw this post from Tom Lane
> http://archives.postgresql.org/pgsql-performance/2004-04/msg00249.php
> and several other references to problem with Xeon MP and I suspect our
> problems are related to this.
> We tried to put our production load on a dual standard Xeon on monday
> and it performs far better with the same configuration parameters.
>
> I know that work has been done by Tom for PostgreSQL 8.1 on
> multiprocessor support but I didn't find any information on if it
> solves the problem with Xeon MP or not.
>
> My question is should we expect a resolution of our problem by
> switching to 8.1 or will we still have problems and should we consider
> a hardware change? We will try to upgrade next tuesday so we will have
> the real answer soon but if anyone has any experience or information
> on this, he will be very welcome.
>
> Thanks for your help.
>
> --
> Guillaume
>
Guillaume,
We had a similar problem with poor performance on a Xeon DP and
PostgreSQL 7.4.x. 8.0 came out in time for preliminary testing but
it did not solve the problem and our production systems went live
using a different database product. We are currently testing against
8.1.x and the seemingly bizarre lack of performance is gone. I would
suspect that a quad-processor box would have the same issue. I would
definitely recommend giving 8.1 a try.
Ken
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-performance@postgresql.org
Cc: ktm@it.is.rice.edu, guillaume.smet@gmail.com
Subject: Re: PostgreSQL and Xeon MP
In-Reply-To: <20060316143020.GW22830@it.is.rice.edu>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox