Re: [PATCH] 2.6.0 batch scheduling, HT aware

[Nick Piggin <piggin@cyberone.com.au>]

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