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

Paul Jackson
2004-10-10T05:14:37Z

> That makes no sense to me whatsoever, I'm afraid. Why if they were allowed
> "to steal a few cycles" are they so fervently banned from being in there?

One substantial advantage of cpusets (as in the kernel patch in *-mm's
tree), over variations that "just poke the affinity masks from user
space" is the task->cpuset pointer. This tracks to what cpuset a task
is attached. The fork and exit code duplicates and nukes this pointer,
managing the cpuset reference counter.

It matters to batch schedulers and the like which cpuset a task is in,
and which tasks are in a cpuset, when it comes time to do things like
suspend or migrate the tasks currently in a cpuset.

Just because it's ok to share a little compute time in a cpuset doesn't
mean you don't care to know who is in it.

--
I won't rest till it's the best ...
Programmer, Linux Scalability
Paul Jackson <pj@sgi.com> 1.650.933.1373