What is the underlying strategy for calculating CPU utilization on HP-UX(ia64)?

[edwardyangxin]

As we know, the command glance , ps , etc. provides the information about total cpu util. Where does these data come from?

Is there a monitor on CPU unit (ia64) and the monitor records the CPU data basing on a certain strategy?

On IBM processors (POWER), there is a PURR (PURR stands for Processor Utilization Resource Register.) which  takes this role. What about ia64 processors?

[Dennis Handly]

>Where does these data come from?

I assume it comes from the HP-UX scheduler.  And you can call pstat(2) to get it.

>What about ia64 processors?

Caliper uses these PMU registers for more details.

[edwardyangxin]

Thanks.

Is there any further information on how PMU monitors the CPU util? like sampling CPU util every 10ms on each core or something like that

I've searched it on google before but got no idea yet...

[Dennis Handly]

>Is there any further information on how PMU monitors the CPU util?

The PMU is part of the CPU, so it measures the different pipeline phases, etc.  Perhaps too low level for your needs.

Look at the Intel docs.  Also look into caliper.