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Date: Tue, 03 Apr 2001 21:21:57 -0700
From: Fabio Riccardi <fabio@chromium.com>
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To: Mike Kravetz <mkravetz@sequent.com>
CC: Ingo Molnar <mingo@elte.hu>, frankeh@us.ibm.com,
        Linux Kernel List <linux-kernel@vger.kernel.org>,
        Alan Cox <alan@lxorguk.ukuu.org.uk>
Subject: Re: a quest for a better scheduler
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I was actually suspecting that the extra lines in your patch were there for a
reason :)

A few questions:

What is the real impact of a (slight) change in scheduling semantics?

Under which situation one should notice a difference?

As you state in your papers the global decision comes with a cost, is it worth it?

Could you make a port of your thing on recent kernels?
I tried and I failed and I don't have enough time to figure out why, that should be
trivial for you though.

TIA, ciao,

 - Fabio

Mike Kravetz wrote:

> On Tue, Apr 03, 2001 at 05:18:03PM -0700, Fabio Riccardi wrote:
> >
> > I have measured the HP and not the "scalability" patch because the two do more
> > or less the same thing and give me the same performance advantages, but the
> > former is a lot simpler and I could port it with no effort on any recent
> > kernel.
>
> Actually, there is a significant difference between the HP patch and
> the one I developed.  In the HP patch, if there is a schedulable task
> on the 'local' (current CPU) runqueue it will ignore runnable tasks on
> other (remote) runqueues.  In the multi-queue patch I developed, the
> scheduler always attempts to make the same global scheduling decisions
> as the current scheduler.
>
> --
> Mike Kravetz                                 mkravetz@sequent.com
> IBM Linux Technology Center

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