Re: [RFC] Patch for isolated scheduler domains

[Nick Piggin <nickpiggin@yahoo.com.au>]

Jesse Barnes wrote:
> On Saturday, July 24, 2004 1:26 am, Nick Piggin wrote:
> 
>>You might have the theoretical problem of ending up with more than
>>one disjoint top level domain (ie. no overlap, basically partitioning
>>the CPUs).
> 
> 
> Yes, we'll have several disjoint per-node cpu spans for a large system, but 
> nearby nodes *will* overlap with more distant nodes than any given node, so I 
> think we're covered, unless I'm misunderstanding something.
> 

No, I'm sure you are covered. The situation I thought of would be
something like the following:

CPUs 0-63, all within distance 4 --- gap distance 5 --- CPUs 64-127.

Where you wouldn't have any overlap between the two sets of CPUs.
This is probably not applicable to you though.

> 
>>No doubt you could come up with something provably correct, however
>>it might just be good enough to examine the end result and check that
>>it is good. At least while you test different configurations.
> 
> 
> Right.  And ultimately, I think we'll want the hierarchy I mentioned in the 
> comments, that'll cover us a little better I think.
> 

Yeah I would agree. No doubt you could spend a long time on improving
it. Start simple so you have a baseline of course.

If you're going to be looking at this, take a look at the way we're
building domains in the "[PATCH] consolidate sched domains" patch I
posted the other day. It may simplify your job as well, for example if
you can make use of the init_sched_build_groups function.