Re: Ideas for a new io scheduler for desktop

From: Pedro Larroy
Date: Tue Nov 09 2004 - 21:12:14 EST


On Tue, Nov 09, 2004 at 08:50:19PM -0500, Robert Love wrote:
> On Wed, 2004-11-10 at 02:32 +0100, Pedro Larroy wrote:
>
> > I think that a new io-scheduler that gave priority to bursty access to
> > block devices would be interesting for desktop and workstation use, and
> > even for some servers.
> >
> > I'm often waiting for graphical aplications, vim, mutt, and almost every
> > program to which I have to interact with because they are blocked
> > waiting for just a few blocks of IO that won't get served fast just
> > because there's a single process hog that's provoking that high latency.
> >
> > In network terminology the disk just feel like a network interface without QoS,
> > service time just goes up insanely with just one client in the queue.
> >
> > Although much care should be taken in designing this algorithm to
> > prevent unfairness, I believe there's room for improvement in this area.
> >
> > I'd like to read about your opinions.
>
> What you are seeing is the affect of read requests being synchronous,
> and thus the pain of read latency, and write requests to one part of the
> disk starving other requests.
>
> Have you tried the new 2.6 I/O schedulers? They should prevent this
> problem.
>
> If you are using 2.6, then your problem might not lie with the I/O
> scheduler. Read request deadlines are very low in both the deadline and
> anticipatory I/O scheduler.
>
> Robert Love
>

Yes, I use them in all of my boxes.

Regards.
--
Pedro Larroy Tovar | Linux & Network consultant | pedro%larroy.com
Make debian mirrors with debian-multimirror: http://pedro.larroy.com/deb_mm/
* Las patentes de programación son nocivas para la innovación *
http://proinnova.hispalinux.es/
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