Re: pcp updates: pmdaproc, cgroups, books

["Frank Ch. Eigler" <fche@xxxxxxxxxx>]

Hi -

On Mon, Dec 15, 2014 at 01:36:03AM -0500, Nathan Scott wrote:
> [...]
> > In an echo of early problems with the papi-pmda qa, this style makes
> > leaks difficult to find, because they are so ephemeral: you can't just
> > do a pminfo loop to exhaust the resources, because they are recreated
> > anew for each pminfo!
> 
> The problem is the choice of client tool, not an inherent limitation of
> the testing as you're suggesting.  The case you're reproducing here is
> calling for a long-running client that issues many fetches, but you're
> coming at it with pminfo - try pmval instead?

Yes, except that pmval is limited to a single metric per invocation.
A single "pminfo cgroup" run can exercise all metrics, and "pminfo
cgroup cgroup cgroup ..." can endurance-test all metrics, not just the
one that we found/fixed this leak in, so it's more forward-looking.

It's not the batch-fetching aspect of pminfo that made this test
workable, but its willingness to traverse a PMNS hierarchy.  (For that
matter, repeatedly traversing the -entire- PMNS would be a good
endurance test for PMDAs and PMCD, as noted in an earlier email.)

- FChE