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

[Matthew Dobson <colpatch@us.ibm.com>]

On Tue, 2004-10-05 at 02:26, Simon Derr wrote:
> I'd like to present you at this point what was the original decision for 
> having exclusive (called strict, at this point in history) and 
> non-exclusive cpusets.
> 
> The idea was to have a system, and run all jobs on it through a batch 
> scheduler. Some jobs cared about performance, some didn't.
> 
> The ones who cared about performance got an 'exclusive' cpuset, the ones 
> who didn't got a 'non exclusive' cpuset.

It sounds to me (and please correct me if I'm wrong) like 'non
exclusive' cpusets are more like a convenient way to group tasks than
any sort of performance or scheduling imperative.  It would seem what
we'd really want here is a task grouping functionality, more than a
'cpuset'.  A cpuset seems a bit heavy handed if all we want to do group
tasks for ease of administration.


> There are still processes running outside the job cpusets (i.e in the root 
> cpuset), sshd, the batch scheduler. These tasks use a low amount of CPU, 
> so it is okay if they happen to run inside even 'exclusive' cpusets. For 
> us, 'exclusive' only means that no other CPU-hungry job is going to share 
> our CPU.

If that's all 'exclusive' means then 'exclusive' is a poor choice of
terminology.  'Exclusive' sounds like it would exclude all tasks it is
possible to exclude from running there (ie: with the exception of
certain necessary kernel threads).

-Matt