From: Tom Lane <tgl@sss.pgh.pa.us>
To: Laszlo Nagy <gandalf@designaproduct.biz>
Cc: pgsql-performance@postgresql.org
Subject: Re: Poor performance on seq scan
Date: Tue, 12 Sep 2006 16:48:57 -0400
Message-ID: <21446.1158094137@sss.pgh.pa.us> (raw)
In-Reply-To: <4506EA84.4070200@designaproduct.biz>
References: <450684EC.4090304@designaproduct.biz>
<17034.1158079926@sss.pgh.pa.us>
<4506EA84.4070200@designaproduct.biz>
Laszlo Nagy <gandalf@designaproduct.biz> writes:
> Tom Lane wrote:
>> Why is that showing 85+ percent *system* CPU time??
> I'm sorry, this was really confusing. I don't know what it was -
> probably a background system process, started from cron (?). I retried
> the same query and I got this:
> [ around 80% idle CPU, 10% system, < 10% user ]
OK, so then the thing really is I/O bound, and Luke is barking up the
right tree. The system CPU percentage still seems high though.
I wonder if there is a software aspect to your I/O speed woes ...
could the thing be doing PIO instead of DMA for instance?
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, gandalf@designaproduct.biz
Subject: Re: Poor performance on seq scan
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