kent- i second steve's comments.. if you take a look at this slide from a talk that i gave you'll see what's going on with multicast...
http://ganglia.sourceforge.net/talks/lug_lbl_talk/html/slide_6.html .. using separate multicast channels will allow for hardward filtering at the datalink layer. if you use different ports the message passes all the way up to the UDP protocol layer before it is dropped or processed. good luck -- matt Today, Steven Wagner wrote forth saying... > a. Definitely a. > > When a host opens a multicast socket, the kernel sends a join message *for > that IP* and should start receiving traffic for that multicast network from > that point on. Listening on different ports... hmmm, that didn't work the > last time I tried it, but I'm pretty sure that it would at least reach the > kernel. > > So if you want to cut down on your multicast traffic, use a different > multicast IP per cluster - that's the way to do it... > > Kent IV, William (WW) wrote: > > My IP multicasting background is a bit lacking, so I'll pose the question > > here. > > > > Background: > > I have a flat network space with 4 clusters of various sizes (16 - 72 > > nodes/ea.). I'm monitoring each cluster individually (i.e. Penguin = nodes > > p1 - 16, Marvin = nodes m1 - m24, etc.) > > > > Question: > > Which configuration option (if either) would reduce the CPU interrupts on > > my cluster nodes? > > a. Configuring each cluster to use it's own multicast channel > > (mcast_channel) through /etc/gmond.conf > > b. Configuring each cluster to use it's own multicast port > > (mcast_port) on one shared channel. > > > > I'm currently doing (b), but I think (a) might help. > > > > This isn't really a Ganglia question, rather an IP Multicast question. > > Does the CPU get interrupted for all multicasts, only those for channels > > it's participating in, or only for channels/ports it's participating in? > > > > My multicast knowledge all derives from DECnet and I'm trying to block that > > out. Thanks for any assistance or advice anyone might be able to provide. > > > > Bill > > > > ----------------------------------------------------------------------------------- > > Bill Kent > > The Dow Chemical Company > > > > > > > > ------------------------------------------------------- > > This SF.net email is sponsored by: > > The Definitive IT and Networking Event. Be There! > > NetWorld+Interop Las Vegas 2003 -- Register today! > > http://ads.sourceforge.net/cgi-bin/redirect.pl?keyn0001en > > _______________________________________________ > > Ganglia-general mailing list > > Ganglia-general@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/ganglia-general > > > > > ------------------------------------------------------- > This SF.net email is sponsored by: > The Definitive IT and Networking Event. Be There! > NetWorld+Interop Las Vegas 2003 -- Register today! > http://ads.sourceforge.net/cgi-bin/redirect.pl?keyn0001en > _______________________________________________ > Ganglia-general mailing list > Ganglia-general@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/ganglia-general >
