Re: multi-queue scheduler update

From: Andi Kleen (ak@suse.de)
Date: Thu Jan 18 2001 - 20:48:21 EST


On Fri, Jan 19, 2001 at 02:35:02AM +0100, Andrea Arcangeli wrote:
> On Thu, Jan 18, 2001 at 08:00:16PM -0500, Mark Hahn wrote:
> > > > microseconds/yield
> > > > # threads 2.2.16-22 2.4 2.4-multi-queue
> > > > ------------ --------- -------- ---------------
> > > > 16 18.740 4.603 1.455
> > >
> > > I remeber the O(1) scheduler from Davide Libenzi was beating the mainline O(N)
> >
> > isn't the normal case (as in "The Right Case to optimize")
> > where there are close to zero runnable tasks? what realistic/sane
> > scenarios have very large numbers of spinning threads? all server
> > situations I can think of do not. not volanomark -loopback, surely!
>
> This is why the numbers with 2/4/8 threads in the runqueue are the most
> interesting ones 8)

With Arjan's patch to use prefetching for the runqueue scan the numbers
will be likely different [at least on cpus that can benefit from prefetching
like p2+ or athlon]

-Andi
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