On Thu, Jun 20, 2002 at 12:07:27PM -0700, Greywolf wrote:
> As a non-kernel non-engineer (I know just enough to be dangerous), it

I'm in about the same boat...

> Anyway, wouldn't it still be best to order the writes per disk rather
> than per partition?

I halfway agree, since I didn't understand the mechanics of assigning
priorities to partitions when the thread started...  If it was going
to be purely automatic, then I don't see much of a point.  swap could
be higher-priority than regular files, but after that I don't see how
the system can understand the optimal I/O load for an arbitrary host.
But allowing an admin to set priority in the fstab (for example) gives
the tools necessary so that s/he can optimise the partitions for
his/her applications...  Which s/he's probably doing already, anyway.

> An I/O scheduler, would that be something like the process scheduler
> where the more contiguous time a write process has, the lower its
> priority gets on the I/O end?

That was my original conception.

> I think it should apply to hard drives only, personally, as if you do
> something like that with a CD-RW, you run the risk of an underrun.
> But, then, what do I know?

I don't think this is a concern...  On a CD-RW, only one process would
typically be writing to the device, so there's no need to allow other
processes access to the drive.

--aidan