On Thu, Jan 22, 2009 at 16:57, Lorin Hochstein <[email protected]> wrote: > For CPU usage (e.g. mulitcpu_user0) , I was expecting output like when > you run 'top' and hit '1', where maximum possible CPU usage is 100% > for each processor.
This is, essentially, the "Solaris mode" of displaying CPU % where the sum total over all CPUs will equal 100%. This is as opposed to the "Irix mode", where each CPU can report up to 100% each; so on a 4-way SMP system, you can, in total, have 400% usage. > 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. -- Jesse Becker GPG Fingerprint -- BD00 7AA4 4483 AFCC 82D0 2720 0083 0931 9A2B 06A2 ------------------------------------------------------------------------------ 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
