Subject: Re: Limiting disk I/O?
To: Tech-kern <>
From: Jukka Marin <>
List: tech-kern
Date: 11/12/2007 14:44:40
On Mon, Nov 12, 2007 at 01:16:39PM +0100, Joerg Sonnenberger wrote:
> Have you tried using a different IO scheduler?

No, but I'm willing to try.

> There are kernel options
> to give priority sorting and read-optimised scheduling. You can select
> the policy for a device with dkctl $dev strategy.

It seems my kernel is lacking something..
# dkctl ld1 strategy
dkctl: /dev/rld1d: DIOCGSTRATEGY: Inappropriate ioctl for device

I'll see if I can find the problem ;)

> The default is first
> come, first serve. It can also help to disable softdep :-)

Softdep is a big win most of the time.  Disabling it "fixes" the problem I
described, but it also makes all disk I/O much slower.