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List:       linux-kernel
Subject:    Re: [Lse-tech] [PATCH] cpusets - big numa cpu and memory placement
From:       Nick Piggin <nickpiggin () yahoo ! com ! au>
Date:       2005-02-09 2:53:05
Message-ID: 42097B11.4090906 () yahoo ! com ! au
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Matthew Dobson wrote:
> Nick Piggin wrote:

>> I didn't really follow where that idea went, but I think at least
>> a few people thought that sort of functionality wasn't nearly
>> fancy enough! :)
> 
> 
> Well, that's about how far the idea was supposed to go. ;)  I think 
> named hierarchical sched_domains would offer the same functionality (at 
> least for CPU partitioning) as CPUSETs.  I'm not sure who didn't think 
> it was fancy enough, but if you or anyone else can describe CPUSETs 
> configurations that couldn't be represented by sched_domains trees, I'd 
> be very curious to hear about them.
> 

OK. Someone mentioned wanting to do overlapping sets of CPUs. For
example, 3 groups, first can run on cpus 0 and 1, second 1 and 2,
third 2 and 0. However this in itself doesn't preculde the use of
sched-domains.

In the (hopefully) common case where there are disjoint partitions
_somewhere_, sched domains can do the job in a much better
way than task cpu affinities (better isolation, multiprocessor
balancing shouldn't break down).

Those users with overlapping CPU sets can then use task affinities
on top of sched domains partitions to get the desired result.

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