Re: [PATCH] 2.6.0 batch scheduling, HT aware

[Nick Piggin]

Nakajima, Jun wrote:

> Today utilization of execution resources of a logical processor is
> around 60% as you can find in public papers, and it's dependent on the
> processor implementation and the workload. It could be higher in the
> future, and their relative priority could be much higher then. So I
> don't think it's a good idea to hard code such a implementation-specific
> factor into the generic scheduler code.

No. The mechanism would be generic, but the parameters would be
arch specific as part of my sched domains patch (if I have anything
to do with it!)

> Regarding H/W-based priority, I'm not sure it's very useful especially
> because so many events happen inside the processor and a set of the
> execution resources required changes very rapidly at runtime, i.e. the
> H/W knows what it should do to run faster at runtime, and imposing
> priority on those logical processor could make them run slower.
>
> I think a software priority-based solution like the below would be more
> generic and work better.

I wouldn't pretend to know about hardware, but it seems like much nicer
than doing it in software. Anyway, if there is hardware out there without
priorities then it would be a good idea to code for it.

Nick

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