Re: [patch] sched-2.5.59-A2

From: Ingo Molnar (
Date: Mon Jan 20 2003 - 04:28:27 EST

On Sun, 19 Jan 2003, Erich Focht wrote:

> The results:
> - kernbench UserTime is best for the 2.5.59 scheduler (623s). IngoB0
> best value 627.33s for idle=20ms, busy=2000ms.
> - hackbench: 2.5.59 scheduler is significantly better for all
> measurements.
> I suppose this comes from the fact that the 2.5.59 version has the
> chance to load_balance across nodes when a cpu goes idle. No idea what
> other reason it could be... Maybe anybody else?

this shows that agressive idle-rebalancing is the most important factor. I
think this means that the unification of the balancing code should go into
the other direction: ie. applying the ->nr_balanced logic to the SMP
balancer as well.

kernelbench is the kind of benchmark that is most sensitive to over-eager
global balancing, and since the 2.5.59 ->nr_balanced logic produced the
best results, it clearly shows it's not over-eager. hackbench is one that
is quite sensitive to under-balancing. Ie. trying to maximize both will
lead us to a good balance.


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