Re: PostgreSQL VACCUM killing CPU

On Tue, May 09, 2006 at 03:19:08AM -0700, blender@jaskom.pl wrote:
> 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?

It's killing your disk drives instead of CPU(which is mostly _idle_
waiting for I/O completion).

Run this command to get an idea of the I/O activities:
        iostat -x 3 3

[AD]Running a kernel patched with adaptive read-ahead may help it:
http://www.vanheusden.com/ara/adaptive-readahead-11.1-2.6.16.5.patch.gz