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Re: Low CPU Usage

From: "Scott Marlowe" <scott(dot)marlowe(at)gmail(dot)com>
To: "brauagustin-susc(at)yahoo(dot)com(dot)ar" <brauagustin-susc(at)yahoo(dot)com(dot)ar>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: Low CPU Usage
Date: 2007-09-19 19:41:45
Message-ID: dcc563d10709191241q3c861ee9td56e409452411059@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-performance
On 9/19/07, brauagustin-susc(at)yahoo(dot)com(dot)ar <brauagustin-susc(at)yahoo(dot)com(dot)ar> wrote:
>
>
> No, changing to fsync off didn't improve performance at all.
>
> Settings
> work_mem = 64MB
> max_stack_depth = 7MB #in the old server is 8MB but if I set in here give me
> the ulimit error
> max_fsm_pages = 204800
> effective_cache_size = 512MB
> Atuvacuum is off.
>
> I have run vacuum full and vacuum analyze. The databases are freezed (there
> are no insert, update or delete operations)!!!
> In both servers the query plans are identical with the same costs too!!!
>
> It's really weird, I don't see high values monitoring disk. Cpu usage is
> about 5% and sometimes a tips of 40 % of disk usage when the query is
> finishing (the first 3 minutes there are some tips of 11 to 16%).

(please don't top post)

This sounds like you've got problems somewhere in your I/O system.
hdparm etc may or may not be seeing the issue.  What do you see in
/var/log/messages or dmesg?

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