From: Matthew Lunnon <mlunnon@rwa-net.co.uk>
To: Sven Geisler <sgeisler@aeccom.com>
Cc: pgsql-performance@postgresql.org
Subject: Re: Limited performance on multi core server
Date: Wed, 12 Dec 2007 12:27:24 +0000
Message-ID: <475FD3AC.1030207@rwa-net.co.uk> (raw)
In-Reply-To: <475FCF1E.7030608@aeccom.com>
References: <475FB50B.8060701@rwa-net.co.uk>
<475FCF1E.7030608@aeccom.com>
Hi Sven,
yes the patch would be great if you could send it to me, we have already
had to compile postgres to up the number of function parameters from 32
to 64.
Meanwhile I will try and persuade my colleagues to consider the upgrade
option.
Thanks
Matthew
Sven Geisler wrote:
> Hi Matthew,
>
> I remember that I also an issue with AMD Opterons before Pg 8.1
> There is a specific Opteron behaviour on shared memory locks which adds
> a extra "penalty" during the execution time for Pg code before 8.1.
> I can you provide my patch for Pg 8.0 which should be adaptable for Pg
> 7.4 if you can compile PostgreSQL.
>
> But if you can upgrade you should upgrade to Pg 8.2.5 64-bit. The scale
> up for your concurrent queries will be great.
>
> Sven.
>
> Matthew Lunnon schrieb:
>
>> Hi,
>>
>> I have a 4 * dual core 64bit AMD OPTERON server with 16G of RAM, running
>> postgres 7.4.3. This has been recompiled on the server for 64 stored
>> procedure parameters, (I assume this makes postgres 64 bit but are not
>> sure). When the server gets under load from database connections
>> executing reads, lets say 20 - 40 concurrent reads, the CPU's seem to
>> limit at about 30-35% usage with no iowait reported. If I run a simple
>> select at this time it takes 5 seconds, the same query runs in 300
>> millis when the server is not under load so it seems that the database
>> is not performing well even though there is plenty of spare CPU. There
>> does not appear to be large amounts of disk IO and my database is about
>> 5.5G so this should fit comfortably in RAM.
>>
>> changes to postgresql.sql:
>>
>> max_connections = 500
>> shared_buffers = 96000
>> sort_mem = 10240
>> effective_cache_size = 1000000
>>
>> Does anyone have any ideas what my bottle neck might be and what I can
>> do about it?
>>
>> Thanks for any help.
>>
>> Matthew.
>>
>> ---------------------------(end of broadcast)---------------------------
>> TIP 6: explain analyze is your friend
>>
>
>
--
Matthew Lunnon
Technical Consultant
RWA Ltd.
mlunnon@rwa-net.co.uk
Tel: +44 (0)29 2081 5056
www.rwa-net.co.uk
--
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: mlunnon@rwa-net.co.uk, sgeisler@aeccom.com
Subject: Re: Limited performance on multi core server
In-Reply-To: <475FD3AC.1030207@rwa-net.co.uk>
* 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