Jeff Mohler wrote:
All I can say is that ontap CPU measurement is not as clear cut as you'd think it is or could be.
Indeed. :-) The definition is, still to this day AFAIK:
"For systems running Data ONTAP versions 7.2.1 or later, the cpu_busy counter is the greater of either average CPU utilization or the busiest domain."
So the obscurity lies in this bit: the busiest domain. What's the exact definition of that? Serial Kahuna (= the column in output of sysstat -M named Kahuna) is very important and has been for a very long time so it comes into play. But it's partly parallelised in a complicated way and that's what makes cpu_busy so "wrong" or... convoluted... or....
About the last time 'the number' meant something accurate, was when there was 1 cpu, and 1 core.
Mmm, that depends on what you mean by "accurate" :-) Like someone at NetApp wrote to me, on this very subject quoting ex US president B Clinton: "it depend on what the definition of 'is', is" ;-)
If someone would like to discuss in detail what the formula used to calculate the value in system:system:cpu_busy actually is, I can take that discussion in a separate e-mail conversation. I know pretty accurately for 8.0.x, not entirely sure what it is for 8.1.1 (waffinity completely re-done there making things far more complex than ever before)
/M