From: Erich Focht <efocht@hpce.nec.com>
To: lse-tech@lists.sourceforge.net, colpatch@us.ibm.com
Subject: Re: [Lse-tech] [RFC PATCH] scheduler: Dynamic sched_domains
Date: Fri, 8 Oct 2004 12:14:20 +0200
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Cc: Paul Jackson <pj@sgi.com>, "Martin J. Bligh" <mbligh@aracnet.com>,
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Hi Matthew,

On Thursday 07 October 2004 02:51, Matthew Dobson wrote:
> 1) Rip out sched_groups and move them into the sched_domains.
> 2) Add some reference counting, and eventually locking, to
> sched_domains.
> 3) Rewrite & simplify the way sched_domains are built and linked into a
> cohesive tree.
> 
> This should allow us to support hotplug more easily, simply removing the
> domain belonging to the going-away CPU, rather than throwing away the
> whole domain tree and rebuilding from scratch. ?This should also allow
> us to support multiple, independent (ie: no shared root) domain trees
> which will facilitate isolated CPU groups and exclusive domains. ?I also
> hope this will allow us to leverage the existing topology infrastructure
> to build domains that closely resemble the physical structure of the
> machine automagically, thus making supporting interesting NUMA machines
> and SMT machines easier.

more flexibility in building the sched_domains is badly needed, so
your effort towards providing this is the right step. I'm not sure
yet whether your big change is really (and already) a simplification,
but what you described sounded for me like getting the chance to
configure the sched_domains at runtime, dynamically, from user
space. I didn't notice any user interface in your patch, or overlooked
it. Could you please describe the API you had in mind for that?

Regards,
Erich

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