Re: [patch -mm v2] cpusets: add memory_slab_hardwall flag

From: Christoph Lameter
Date: Thu Mar 12 2009 - 12:19:07 EST


On Tue, 10 Mar 2009, David Rientjes wrote:

> > The description is not accurate. This feature is only useful if someone
> > comes up with a crummy cpuset definition in which a processor is a member
> > of multiple cpusets and thus the per cpu queues of multiple subsystems get
> > objects depending on which cpuset is active.
> >
>
> Cpusets are hierarchical, so it is quite possible that a parent cpuset
> will include a group of cpus that has affinity to a specific group of
> mems. This isolates that cpuset and all of its children for NUMA
> optimiziations. Within that, there can be several descendant cpusets that
> include disjoint subsets of mems to isolate the memory that can be used
> for specific jobs.

Yes cpusets are hierachical for management purposes but it is well known
that overlaying cpusets for running applications can cause issues with the
scheduler etc. Jobs run in the leaf not in the higher levels that may
overlap.
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