I don't have firsthand experience, so I may be way off on this. However, my understanding goes like this:
It's not that gmond itself consumes any huge (or even significant) amount of cpu time. These clusters run massively parallel programs that have synchronization points (frequently). When these points are reached in the code, all participating cpus have to wait... and thus a tiny and randomly occurring disruption on any or all of the nodes ends up getting multiplied significantly because all the rest of the nodes may have to wait for each disruption. When the parallelism gets large, they care about very short disruptions.... On Oct 16, 2008, at 1:27 PM, john allspaw wrote: > > I don't want to reply there, but... > > reports in that thread of gmond creating 20-50% overhead? I can't > imagine that at all, and since the discussion devolved into "I hate > XML", it doesn't sound like such a productive discussion. How could > it be possible for gmond to take that much of a hit? Maybe it's > time I grabbed some stats from one of our database machine which has > gazillions of MySQL gmetrics.... > > -j > > > ----- Original Message ---- >> From: Bernard Li <[EMAIL PROTECTED]> >> To: ganglia-developers <ganglia-developers@lists.sourceforge.net> >> Sent: Tuesday, September 23, 2008 10:43:59 AM >> Subject: [Ganglia-developers] Ganglia discussion in Beowulf mailing- >> list >> >> Howdy! >> >> There is a discussion going on in Beowulf mailing-list which touches >> on Ganglia -- some of you may find it interesting: >> >> http://www.beowulf.org/pipermail/beowulf/2008-September/thread.html#23239 >> >> Cheers, >> >> Bernard >> >> ------------------------------------------------------------------------- >> This SF.Net email is sponsored by the Moblin Your Move Developer's >> challenge >> Build the coolest Linux based applications with Moblin SDK & win >> great prizes >> Grand prize is a trip for two to an Open Source event anywhere in >> the world >> http://moblin-contest.org/redirect.php?banner_id=100&url=/ >> _______________________________________________ >> Ganglia-developers mailing list >> Ganglia-developers@lists.sourceforge.net >> https://lists.sourceforge.net/lists/listinfo/ganglia-developers > > > > > > ------------------------------------------------------------------------- > This SF.Net email is sponsored by the Moblin Your Move Developer's > challenge > Build the coolest Linux based applications with Moblin SDK & win > great prizes > Grand prize is a trip for two to an Open Source event anywhere in > the world > http://moblin-contest.org/redirect.php?banner_id=100&url=/ > _______________________________________________ > Ganglia-developers mailing list > Ganglia-developers@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/ganglia-developers ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Ganglia-developers mailing list Ganglia-developers@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ganglia-developers
