Collector Command

    Enables the collection of vector program counter sampling data.

    Format

      SET VPC_SAMPLING

1  –  Description

    The SET VPC_SAMPLING Collector command enables the collection of
    PC values for random vector instructions and causes the sampling
    rate to be applied to the wall clock. The collected data lets you
    determine the scalar/vector parallelism throughout your entire
    program.

    When you collect vector PC samples, the sampling interval timer
    includes all idle time associated with the current run of the
    program. This form of sampling shows you where the time is being
    spent in the program with little cost to the time of actually
    running the program. time. You can set the time interval by using
    the /INTERVAL qualifier.

2  –  Qualifiers

2.1    /INTERVAL

       /INTERVAL:n

    Specifies the sampling interval in milliseconds. The value of
    n must be at the least 10 milliseconds and at the most 60,000
    milliseconds. Because the granularity of the system clock is 10
    milliseconds, use a multiple of 10. The default sampling interval
    is 10 milliseconds; therefore, you can use the /INTERVAL:n
    qualifier only to specify a longer sampling interval.

2.2    /STACK_PCS

    Specifies that stack PC values for vector PC data are to be
    collected. The /STACK_PCS qualifier is the default upon entry
    into the Collector.

2.3    /NOSTACK_PCS

    Specifies that stack PC values for vector PC data are not to be
    collected. If you specify /NOSTACK_PCS, further SET VPC_SAMPLING
    requests assume a default of /NOSTACK_PCS.

3  –  Examples

  PCAC> SET VPC_SAMPLING/INTERVAL:20/NOSTACK_PCS

      This command causes the interval to be 20 milliseconds, and
      disables STACK_PCS collection for this measurement. For all
      further SET VPC_SAMPLING requests, a default of /NOSTACK_PCS
      will be assumed.