On Fri, Jan 23, 2009 at 09:15:16AM -0500, Lorin Hochstein wrote: > On Jan 22, 2009, at 7:02 PM, Jesse Becker wrote: > > > On Thu, Jan 22, 2009 at 16:57, Lorin Hochstein <[email protected]> > > wrote: > > >> Instead, the ganglia metrics effectively divide the CPU usage metrics > >> by number of CPUs. For example, if there are 2 CPUs, the maximum > >> value > >> of multicpu_user0 seems to be 50%, if there are 4 CPUs, the maximum > >> value is 25%, etc. > >> > >> Is there a reason why the chosen denominator is total time for all > >> CPUs, rather than per CPU like "top"? > > > > It is easier to store. Only two values need to be tracked for all > > hosts: a total CPU value, and number of CPUs. This is essentially > > the "Solaris mode" described above. > > > > It does imply a loss of information. You no longer get specific > > per-CPU values, but tracking this data would require a non-trivial > > change on the backend daemons and webpages to implement. Notice that > > I didn't say "hard," just non-trivial. > > > > Would it be possible to implement things so that the multicpu metrics > are modified to report 100% maximum, but the overall CPU metrics (e.g > cpu_user) remain the way they are now, so that no changes would be > necessary to the backend daemons and webpages?
I think this is a good idea, now that virtualization allows you to easilly hotplug a CPU in a system the maximum of multicpu_userN can change on the fly (assuming that gmond will detect this) which will make the plot almost impossible to read. Metrics like cpu frequency, memory, number of CPUs can not be considered static any more and we need to start adapting to it. Kostas ------------------------------------------------------------------------------ This SF.net email is sponsored by: SourcForge Community SourceForge wants to tell your story. http://p.sf.net/sfu/sf-spreadtheword _______________________________________________ Ganglia-general mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/ganglia-general
