Subject: Re: I/O priorities
To: Aidan Cully <aidan@kublai.com>
From: Manuel Bouyer <bouyer@antioche.lip6.fr>
List: tech-kern
Date: 06/24/2002 22:36:40
On Fri, Jun 21, 2002 at 11:14:10PM -0400, Aidan Cully wrote:
> I've been thinking about this, and I don't think I agree with your
> reasoning.  TCP congestion avoidance works decently, but it's a
> different problem domain: a fundamental characteristic of IP is
> the heterogenous network, and there's no telling at the source
> how much throughput is available for traffic.  That's not the case
> with device I/O, except for network-mounted devices.  I also think
> that TCP congestion avoidance still doesn't deal very well with
> interactive sessions.  Try connecting to the Internet using a 56K
> modem, connecting to a remote host using telnet or ssh, and starting
> a large download at the same time.  See what happens to your telnet
> session, and you're approaching a problem closer to what we'd be
> trying to solve with an I/O scheduler.

And this is why we're now trying to have different queues with priorities
in network routers :)

--
Manuel Bouyer, LIP6, Universite Paris VI.           Manuel.Bouyer@lip6.fr
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