This function will turn cause the interpreter to generate code to
call hooks that are used to profile code. The profile_on
function does not establish those hooks, rather it causes code to be
generated to support such hooks.
With no optional argument, only code to support function call hooks
will be generated. To enable support for line-by-line profile
hooks, a value of 1 should be passed to this function.
This function establishes the profiling hooks and resets or
initializes the profiler state. By default, only hooks to gather
function call information are created. To enable the gathering of
line-by-line information, a value of 1 should be passed to this
function.
This function may be used to ``calibrate'' the profiler. As the
performance of the profiler and the interpreter varies with a
platform and load-dependent manner, this function should be called
prior to enabling the profiler. It tries to determine the average
amount of overhead per statement executed and function call by
executing a series of statements and functions many times to
determine statistically accurate values. The optional parameter
N may be used to control the amount of code executed
for the calibration process. If no value is provided, the N
will default to 1000. The higher the value, the more accurate the
calibration will be and the longer the calibration process will take.
The function may be used to format the profile report and write it
to the specified file. If the file parameter represents a
File_Type file descriptor, then the report will be written
the the descriptor.