Re: Usage up to 50% CPU - Mailing list pgsql-performance

From Magnus Hagander
Subject Re: Usage up to 50% CPU
Date
Msg-id 20070427081350.GD12895@svr2.hagander.net
Whole thread Raw
In response to Re: Usage up to 50% CPU  ("Andres Retzlaff" <andres_retzlaff@hotmail.com>)
Responses Re: Usage up to 50% CPU  (Shane Ambler <pgsql@Sheeky.Biz>)
List pgsql-performance
On Fri, Apr 27, 2007 at 08:10:48AM +0000, Andres Retzlaff wrote:
> Hi Magnus,
>
> in this case each CPU goes up to 50%, giveing me 50% total usage. I was
> specting as you say 1 query 100% cpu.
>
> Any ideas?

No. 1 query will only use 100% of *one* CPU, which means 50% total usage.
You need at least one query per CPU to reach full 100% of the whole system.
(Actually, you can get slightly above 50% since the query will run on one
CPU and the OS and autovacuum and bgwriter can run on the other. But it's
marginally)

//Magnus


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