2 The Profiler (eprof)

2.1 The Profiler (eprof)

The profiler eprof tool is used to profile a system in order to find out how much processing time various processes occupy.

The modules to be profiled must be compiled with the trace flag. The following functions are used to start and stop the eprof server, select modules to be profiled, and display the profiling results.

• start() -> {ok, Pid} | {error, {already_started, Pid}} starts the eprof server
• stop() -> stopped stops the eprof server
• profile(Rootset, Mod, fun, Args) profiles a process
• profile(Rootset) -> profiling | error starts profiling a process
• stop profiling() -> profiling_stopped | profiling_already_stopped stops profiling
• analyse() -> ok displays the profiling results
• total_analyse() -> ok prints the profiling results
• log(File) -> OK activates logging of eprof printouts.

The trace flag slows the system slightly. The part of the system which is profiled runs at approximately 20% of its original speed.