Re: PostgreSQL VACCUM killing CPU

From: Will Reese <wreese(at)rackspace(dot)com>
To: PostgreSQL Performance <pgsql-performance(at)postgresql(dot)org>
Subject: Re: PostgreSQL VACCUM killing CPU
Date: 2006-05-10 03:03:12
Message-ID: 6EAB7E4D-59BC-42B7-93E8-3EE82AE9E4F0@rackspace.com
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The "wa" means waiting on IO. Vacuum is a very IO intensive
process. You can use tools like vmstat and iostat to see how much
disk IO is occurring. Also, sar is very helpful for trending these
values over time.

-- Will Reese http://blog.rezra.com
On May 9, 2006, at 5:19 AM, blender(at)jaskom(dot)pl wrote:

> Hi all !
>
> I have got such problem.
> Im running Postgresql 7.3.2 on Linux 2.6.13.
> What is see when VACCUM is running and killing my CPU is:
>
> Cpu(s): 3.2% us, 0.0% sy, 0.0% ni, 0.0% id, 96.8% wa, 0.0% hi,
> 0.0% si
>
> what i am worry about is "96.8% wa" why is it like that?
>
> what is the process waiting for ?
>
> could somone explain me that please? :)
>
> Best regards
> david
>
>
> ---------------------------(end of
> broadcast)---------------------------
> TIP 5: don't forget to increase your free space map settings

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