Re: [Patch][RFC] Disabling per-tgid stats on task exit in taskstats

[Paul Jackson <pj@sgi.com>]

Shailabh wrote:
> I suppose this is because cpuset's offer some middle ground between 
> collecting data per-cpu vs. collecting it for all cpus ?

Yes - well said.  And I have this strange tendency to see all the
worlds problems as opportunities for cpuset solutions <grin>.

> What happens when someone is using cpusets on such a machine and
> changes its membership in response to other needs.  All taskstats
> users would need to monitor for such changes and adjust their
> processing....seems like unnecessary tying up of two unrelated
> concepts.

I would not expect taskstat users to monitor for such changes.
I'd expect them to monitor the stats from whatever is in the
cpuset they named.  If a task moves out of that cpuset to another,
then tough -- that task will no longer be monitored by that
particular monitoring request.

Cpusets do provide a convenient middle ground, as you say, which
is really useful for reducing scaling issues such as this one to
a managable size.

Per-cpu is too fine grained, and per-system too coarse.

An unnecessary tying - yes.  But perhaps a useful one.

-- 
                  I won't rest till it's the best ...
                  Programmer, Linux Scalability
                  Paul Jackson <pj@sgi.com> 1.925.600.0401