Re: [Lse-tech] [PATCH] cpusets - big numa cpu and memory placement

[Peter Williams <pwil3058@bigpond.net.au>]

Paul Jackson wrote:
> Peter wrote:
> 
>>Of course, this [kernel compile option] makes gradual movement
>>from one model to the other difficult to say the least.
> 
> 
> To say the least.
> 
> It might be possible to continue to support current affinity calls
> (setaffinity/mbind/mempolicy) even while removing the duplication of
> affinity masks between tasks and cpusets.
> 
> If each call to set a tasks affinity resulted in moving that task into
> its very own cpuset (unless it was already the only user of its cpuset),
> and if the calls to load and store task->{cpus,mems}_allowed in the
> implementation of these affinity sys calls were changed to load and
> store those affinity masks in the tasks cpuset instead.
> 
> I'm just brainstorming here ... this scheme could easily have some
> fatal flaw that I'm missing at the moment.

Provided overlapping sets are allowed it should be feasible.  However, 
I'm not a big fan of overlapping sets as it would make using different 
CPU scheduling configurations in each set more difficult (maybe even 
inadvisable) but that's a different issue.

Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce