Re: [ck] Re: [Announce] [patch] Modular Scheduler Core and CompletelyFair Scheduler [CFS]

[Chris Friesen]

Mark Glines wrote:

> One minor question: is it even possible to be completely fair on SMP?
> For instance, if you have a 2-way SMP box running 3 applications, one of
> which has 2 threads, will the threaded app have an advantage here?  (The
> current system seems to try to keep each thread on a specific CPU, to
> reduce cache thrashing, which means threads and processes alike each
> get 50% of the CPU.)

I think the ideal in this case would be to have both threads on one cpu, 
with the other app on the other cpu.  This gives inter-process fairness 
while minimizing the amount of task migration required.

More interesting is the case of three processes on a 2-cpu system.  Do 
we constantly migrate one of them back and forth to ensure that each of 
them gets 66% of a cpu?

Chris
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