Re: [PATCH 12/15] sched: Allow NODE domain to be parent of MCinstead of CPU domain

From: Andreas Herrmann
Date: Tue Aug 25 2009 - 04:56:13 EST

On Mon, Aug 24, 2009 at 05:32:40PM +0200, Peter Zijlstra wrote:
> On Thu, 2009-08-20 at 15:42 +0200, Andreas Herrmann wrote:
> > The level of NODE domain's child domain is provided in s_data.numa_child_level.
> > Then several adaptions are required when creating the domain hierarchy.
> > In case NODE domain is parent of MC domain we have to:
> > - limit NODE domains' span in sched_domain_node_span() to not exceed
> > corresponding topology_core_cpumask.
> > - fix CPU domain span to cover entire cpu_map
> > - fix CPU domain sched groups to cover entire physical groups instead of
> > covering a node (a node sched_group might be a proper subset of a CPU
> > sched_group).
> > - use correct child domain in init_numa_sched_groups_power() when
> > calculating sched_group.__cpu_power in NODE domain
> > - calculate group_power of NODE domain after its child domain
> >
> > Note: As I have no idea when the ALLNODES domain is required
> > I assumed that an ALLNODES domain exists only if NODE domain
> > is parent of CPU domain.
> I think its only used when the regular node level is too large, then we
> split it into smaller bits. SGI folks who run crazy large machines use
> this.


> /me mumbels about renaming the domain level, CPU is the physical socket
> level, right? stupid names.
> Patch sounds funky though, numa_child_level should be effident from the
> tree build.

In the current code the numa_child_level must be known before/while
the tree is built. Of course once the tree is ready, the child domain
is known (apart from degeneration).


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