`perfmon' is a sample program to access the performance-monitoring counters on Pentium and Pentium Pro CPUs. See perfmon(4) for a description of this facility. The program takes the following options: -u count events in user mode -o count events in kernel mode (these two can be combined) -e count events, not duration -l n run `n' loops (default 50) -s n sleep `n' seconds between loop iterations (default 0) The following options are not implemented on Pentium CPUs: -m n use count mask `n' -i invert sense of count mask comparison -U n use unit mask `n' There is one mandatory argument, which is the event number to be monitored, defined in . All numbers can be specified in any format acceptable to strtol(3). $FreeBSD$