Re: [SHED][IO-SHED] Are we missing the big picture?

From: Ihar \ (filia@softhome.net)
Date: Fri Aug 01 2003 - 04:00:04 EST


   Am I right - judging from your posting - that we finally reached
moment than Linux will have network-like queueing disciplines for disks
and CPUs?

   In any way, CPU/disk throughput just another types of limited resource.
   It would be nice to be able to manage it - who gets more, who gets
less. CPU/disk schedulers by manageability are far behind network.
   IMHO must have for servers.

Ian Kumlien wrote:
> Hi all,
>
> I have been following the sheduler and interactivity discussions closely
> but via the marc.theaimsgroup.com archive, So i might be behind etc...
> =P
>
> [Note: sorry if i sound like mr.know-it-all etc, just trying to get a
> point across]
>
> Anyways, i think that the AS discussions that i have seen has missed
> some points. Getting the processes priority in AS is one thing, but fist
> of all i think there should be a stand off layer. Let me explain:
>
> I liked Jens Axobe's 'CBQ' alike implementation (based on the idea of
> Andrea A. (afair i have the names right) since it does the most
> important thing... which is *nothing* when there is no load (ie, pass
> trough).
>
> AS might be/is the best damn io sheduler for loaded machines but when
> there is no load, it's overhead. So in my opinion there should be
> something that first warrants the usage of AS before it's actually
> engaged.
>
> And, if it's only engaged during high load, additions like basing the
> requests priority on the process/tasks priority would make total sense,
> adding the 'wakeup on wait' or what it was would also make total
> sense... But how many of your machines uses the disk 100% of the time?
> (in the real world... )
>
> I don't know how 'CBQ' was implemented but any 'we are under load now'
> trigger would do it for me.
>
> Please see to it that my CC is included in any discussions =)
>
> PS. Or was it a version of SFQ? in that case s/CBQ/SFQ/g
> DS.
>

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