Subject: Re: Limiting disk I/O?
To: Jukka Marin <>
From: Andrew Doran <>
List: tech-kern
Date: 11/12/2007 21:07:34
On Mon, Nov 12, 2007 at 09:24:34AM +0200, Jukka Marin wrote:

> I'm still playing with a server-to-be, equipped with a 3ware 9550SXU RAID
> controller.  I'm having performance problems when manipulating lots of small
> files (like extracting pkgsrc.tar.gz).  With 4 GB of RAM, data fits nicely
> in the buffer cache and when the time comes, it is flushed to disk.  This is
> when the problems begin: The disk (especially RAID5) becomes 100% busy and
> all other disk accesses are severely affected - loading a small binary from
> system disk can take 10...100 seconds, so the system is pretty much dead
> until the cache flush is completed.

This patch is against current but it should apply to netbsd-4, and I think
it may help. If it doesn't apply it's easy to make the changes by hand: