HP OpenVMS Systems

Ask the Wizard Questions

NULL time?

The Question is:

How can I find my cpu null time.
I have a 6000-330 with three active cpus.

We had some code using what we were told are undocumented
features that works on single process units, but not on the
6330. It used the CTime array to calculate the free time.

The Answer is:

    You would have to write code that accesses the per cpu tick
    counters.  The data is Exec read.  The field is CPU$L_NULLCPU, using
    SMP$GL_CPU_DATA as the start, one CPU at a time.  Beware that writing
    K-mode code is like working without a safety net, one mistake and the
    system is down.

    An alternative is to use the undocumented / unsupported $GETSPI system
    service.  Which is what MONITOR uses.

    Neither methods are supported.