On Nov 8, 2007, at 8:32 PM, richard grevis wrote:
Doug,
OK, I gave the paper a careful read. That was good work I must say,
and now I see where you are coming from.
hah, I don't know if I should be happy or sorry for you :) It's
interesting, but a little painful :)
Questions. What is the polling
interval you would use?
we're looking at no more than once a minute
Do you plan multicast?
yes
Anyway -
<snip>
Summary?
Resonance and gmond load spike synchronicity make cause you some
compute jitter on nodes. But if you want to observe load during
calculations, well you want to observe load. And gmond is pretty
lightweight for that task and I am unaware of anything "lighter".
That's good to know.
gmetad level scaling problems are real but can be managed through
SAN or
tmpfs use, grouping nodes to clusters then clusters to grids.
nod, we'll be doing this for certain. Already planned out a box for it.
Aside: Fast ganglia polling requires hacks to remove statically
defined
and long sleeps in several places (to add jitter to threads).
currently, I'm putting together a third category of metric that
ganglia can pull. We've euphemistically called it "collect-on-poke".
In short, nothing on that metric gets collected until you talk to
ganglia in some fashion (still kind of in hand wavey stage here).
This would have the effect of minimizing the jitter as everything
would be happening at the same time. The code is pretty simple, but
I'm still getting it reviewed by other, more experienced coders so as
to verify my sanity.
- richard
--
Doug Nordwall
Unix Administrator
EMSL Computer and Network Support
Unclassified Computer Security
Phone: (509)372-6776; Fax: (509)376-0420
The best book on programming for the layman is "Alice in Wonderland";
but that's because it's the best book on anything for the layman.
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