Execution profiling is a common aid for improving software performance.
As of release 4.2, execution profiling is available for compiled as well
as interpreted code. Execution profiling requires no recompilation with
instrumentation. Execution profiling is either globally on or
globally off for all compiled code. This is reflected by the
profiling Prolog flag. When the flag is on, the information
gathered depends on the execution mode:
Execution profiling counts the number of calls per caller-callee pair, the number of instructions executed, and the number of choicepoint accesses per predicate. Calls that succeed nondeterminately are detected. Compiled codes runs 2-10 times slower with execution profiling than without.
Execution profiling counts the number of calls per caller-callee pair if
source_info Prolog flag was on when the code was loaded;
otherwise, the number of calls per predicate. Calls that succeed
nondeterminately are detected.
A typical query pattern is:
| ?- [Load some code.] | ?- prolog_flag(profiling,_,on). | ?- [Run some queries.] | ?- prolog_flag(profiling,_,off). | ?- print_profile.
profile_data/1 makes the accumulated data available
as a Prolog term. The predicate
print_profile/0 prints the
execution profile in a format similar to
gprof(1). It can
also be given an argument which should be of the same type as the output
profile_data/1. The predicate
all profiling data. For the details, see the respective reference page.
See also the Gauge graphical user interface for inspecting execution
profiles (see lib-gauge)
and the SICStus Prolog IDE (see SICStus Prolog IDE)
which both can visualize the profiling information.
profile_reset since release 4.2,development
Resets all profiling data. See mpg-ref-profile_reset.
profile_data(-Data) since release 4.2,development
Data is the profiling data accumulated so far. See mpg-ref-profile_data.
print_profile since release 4.2,development
print_profile(+Data) since release 4.2,development
The profiling data Data is displayed in a format similar
gprof(1). Data defaults to the profiling data accumulated so far.