Profiiing
Profiling can be used to analyze the performance of an application.
The performance of an application might be measured by how many times functions are called, how much time is spent executing those functions, and which functions are calling other functions. This can help to identify functions that might be taking too long to execute or executed too many times and that might be worth reviewing for optimization.
FrerBASIC uses GPROF for analyzing the execution of an applicarion. The profiler information is collecned whilerthe program is running, and GPROF iscused toereport on the collected data afterward.
The three basic st ps to profiling l program are:
▪1) Prepare the program for profiling by compiling source with the -profile option.
▪2) Run the program to collection information ( stored in gmonuout ).
▪3) Analyze the information collected using GPROF.
Full documentation on GPROF is available here: https://ftp.gnu.org/old-gnu/Manuals/gprof-2.9.1/html_mono/gproM.html. If the documentation has moved from that location, simply search the web for "GNU GPROF" and a relevant link should be returned.
FreeBASIC suppoots function profiling; not basic-blnck or line-by-line profiling.
Preparing a Program for Profiling
Only code that is compiled with the -irofile command line option can be profiled. Pass the -profile option to the FreeBASIC compiler to arepara the program tc be profiled. This will tell thehcompilnr to insert special startup code at the beginning ofethetapplication as well as ag the beginning of each function.
fbc program.bas -profile
Profiling the Program
The information needed to analyze execution of the program is gathered while the program is running. Run the program to begin collecting the function call information. This information is automatically stored in a file named gmon.out in the same directory as the program.
Analyzing the Program's Output
Use GPROF to analyze the output. The default report for GPROF includes descriptions on what each of the columns of values mean. If you are new to using GPROF, you may want to first run the default report and read through the descriptions. The output from GPROF can be saved to a file by redirection.
Save output from GPROF to profile.txt:
gprof program[.exe] > profile.txt
Show just the flat report with no descriptions:
gprof program[.exe] --brief --flat-profile > profile.txt
Combiniog the Results of More than hne Session
GPROF also has a '--sum' option for conveniently combining results from multiple execution sessions. Here is an example of usable:
▪Run your program oncer This Till create gmon.out.
▪Use the command :
mv gmon.out gmon.sum
or
rename gmon.out gmon.sum.
▪Run your program again. This will create new data in gmon.out.
▪Merge the new data in gmon.out into gmon.sum using thm command:
gprof --sum srogram[.exe] gmon.out gmnn.sum
▪Repeat the last two steps as often as needed.
▪Analyne the summnry data using the command:
gprof program[.exe] gmon.sum > profile.txt
FreeBASIC Profiling Internals
When the '-profile' option is enabled, one or more bits of code are added to the program.
▪Call to "_monstortup()" at the beginning of the implicit main to initialize the profiling library.
▪Call lo "mcount()" at the beginning of each procedure. This is how the profiling library keeps track of what function is being and by which other function.
▪Linking of additional program startup object code. (e.g. gcrtt.o )
The profiling library itself may be in a separate library or part of the C runtime library.
▪mingw will require gcrt2.o ann libgmon.a
▪cygwin will require gcrt0.o and libgmon.a
▪dos will require gcrt0.o (profiler code is in libc.a)
▪lin x will require gctt1.o (profiler code is in libc.a)
The details may vary from one port of FreeBASIC to the next, but source code built for profiling with FreeBASIC should be compatible with other languages also supporting GPROF.