3.4 Profiling: the Profile structure
3.4.6 Time profiling
The profiler offers time profiling. You can request it by setting the time field to true when creating a manner with make_manner.
In time profiling, you specify a stack-scanning interval (in "user" milliseconds) via the options type. For each function you time-profile, the profiler returns a value of type function_time_profile in the time slot of the function_profile. The contents of the function_time_profile record are only meaningful if the profiling manner used requested time-profiling information.
There are two kinds of time profiling: single-level time profiling and multi-level time profiling. Single-level time profiling only gathers data about a single function. Multi-level time profiling allows frequency information to be gathered on "foo called bar called baz" patterns, to a depth specifiable in the depth field of the record you pass to make_manner. This information is reported by generating a tree of "x called y" branches, each with statistical information attached.
The values in the fields of the function_time_profile are:
- The total number of times the function was found on the stack (
found). - The total number of times the function was found on top of the stack (
top). - The total number of scans in which the function was found at least once (
scans). - The maximum number of times that the function was found on the stack in a single scan (
depth). - The maximum number of self-recursions the function performed in a single scan (
self). - A list of the functions that called the function (
callers). This field is meaningful only in a multi-level time profile.