Like the profile provider, the cpc provider creates probes dynamically on an as-needed basis. Thus, the desired cpc probe might not appear in a listing of all probes (for example, by using dtrace -l -P cpc) but the probe will be created when it is explicitly enabled.
Specifying a small event overflow count for frequently occurring events (e.g. cycle count, instructions executed) would quickly render the system unusable as a processor would be continuously servicing performance counter overflow interrupts. To prevent this situation, the smallest overflow count that can be specified for any probe is set, by default, at 5000. This can be altered by adjusting the dcpc-min-overflow variable in the /kernel/drv/dcpc.conf configuration file and then unloading and reloading the dcpc driver.