Re: [patch] sched-2.5.59-A2

From: Andrew Theurer (
Date: Mon Jan 20 2003 - 14:13:39 EST

> > I think the large PPC64 boxes have multilevel NUMA as well - two real
> > phys cores on one die, sharing some cache (L2 but not L1? Anton?). And
> > SGI have multilevel nodes too I think ... so we'll still need multilevel
> > NUMA at some point ... but maybe not right now.
> Intel's HT is the cleanest case: pure logical cores, which clearly need
> special handling. Whether the other SMT solutions want to be handled via
> the logical-cores code or via another level of NUMA-balancing code,
> depends on benchmarking results i suspect. It will be one more flexibility
> that system maintainers will have, it's all set up via the
> sched_map_runqueue(cpu1, cpu2) boot-time call that 'merges' a CPU's
> runqueue into another CPU's runqueue. It's basically the 0th level of
> balancing, which will be fundamentally different. The other levels of
> balancing are (or should be) similar to each other - only differing in
> weight of balancing, not differing in the actual algorithm.

I have included a very rough patch to do ht-numa topology. I requires to
manually define CONFIG_NUMA and CONFIG_NUMA_SCHED. It also uses num_cpunodes
instead of numnodes and defines MAX_NUM_NODES to 8 if CONFIG_NUMA is defined.

I had to remove the first check in sched_best_cpu() to get decent low load
performance out of this. I am still sorting through some things, but I
though it would be best if I just post what I have now.

-Andrew Theurer

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