>From: Wojciech Puchar <wojtek@chylonia.3miasto.net>
>To: Manuel Bouyer <bouyer@antioche.lip6.fr>
>CC: Aidan Cully <aidan@kublai.com>, <tech-kern@netbsd.org>
>Subject: Re: I/O priorities
>Date: Thu, 20 Jun 2002 16:01:15 +0200 (CEST)
[...]
> > > seconds for dd if=/dev/zero to flush all of its buffers.
> >
> > An I/O scheduler does probably make sense. Other mechanism can help too.
> > First we probably need a per-partition I/O queue, instead of per device.
>
>i don't think partitions have anything with that. doing that will make
>linux-like case (at least linux 2.2. kernels) where lots of partitions
>means even slower work and lots of disk seeks as it sorts request per
>partition not real device
>

Doesn't NetBSD have ccd's and raid devices? It may not be slower to do 
scheduling on a per partition basis for a single 'disk' in that case. Since 
it will slow down single disks though, how about making the scheduling be 
two-leveled: 1 level for partitions and a second level for physical devices? 
This way, partitions would have the same type of scheduling/priority scheme 
which would then be further influenced by the priority scheme per device?

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