Chapter 19
profile Provider
The profile provider provides probes associated with a time-based interrupt firing every fixed,
specified time interval. These unanchored probes that are not associated with any
particular point of execution, but rather with the asynchronous interrupt event. These probes can
be used to sample some aspect of system state every unit time
and the samples can then be used to infer system behavior. If the
sampling rate is high, or the sampling time is long, an accurate inference
is possible. Using DTrace actions, the profile provider can be used to sample practically
anything in the system. For example, you could sample the state of the
current thread, the state of the CPU, or the current machine instruction.
Note - Thread-local variables are inaccessible to probes from the profile provider. Using the
special identifier self to reference a thread-local variable with such a probe will
produce no output.
