cpc Probe Creation

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 but the probe will be created when it is explicitly enabled. You can use dtrace -l -P cpc for listing all the cpc probes.

Specifying a small event overflow count for frequently occurring events, such as cycle count and number of instructions executed, renders 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.

Note:

Specify high frequency events such as instructions executed or cycle count. For example, measuring busy cycles on a fully utilized 3GHz-processor with a count of 50000 would generate approximately 65000 interrupts/sec. This rate of interrupt delivery could degrade system performance to some degree.