4.2 Analysis Options
- The -a option causes
gprofto suppress the printing of statically declared (private) functions. (These are functions whose names are not listed as global, and which are not visible outside the file/function/block where they were defined.) Time spent in these functions, calls to/from them, etc., will all be attributed to the function that was loaded directly before it in the executable file. This option affects both the flat profile and the call graph.
- The -c option causes the call graph of the program to be
augmented by a heuristic which examines the text space of the object
file and identifies function calls in the binary machine code.
Since normal call graph records are only generated when functions are
entered, this option identifies children that could have been called,
but never were. Calls to functions that were not compiled with
profiling enabled are also identified, but only if symbol table
entries are present for them.
Calls to dynamic library routines are typically not found
by this option.
Parents or children identified via this heuristic
are indicated in the call graph with call counts of 0.
- The -D option causes
gprofto ignore symbols which are not known to be functions. This option will give more accurate profile data on systems where it is supported (Solaris and HPUX for example).
- The -k option allows you to delete from the call graph any arcs from
symbols matching symspec from to those matching symspec to.
- The -l option enables line-by-line profiling, which causes
histogram hits to be charged to individual source code lines,
instead of functions. This feature only works with programs compiled
by older versions of the
gcccompiler. Newer versions of
gccare designed to work with the
If the program was compiled with basic-block counting enabled, this option will also identify how many times each line of code was executed. While line-by-line profiling can help isolate where in a large function a program is spending its time, it also significantly increases the running time of
gprof, and magnifies statistical inaccuracies. See Statistical Sampling Error.
- This option affects execution count output only.
Symbols that are executed less than num times are suppressed.
- The -n option causes
gprof, in its call graph analysis, to only propagate times for symbols matching symspec.
- The -n option causes
gprof, in its call graph analysis, not to propagate times for symbols matching symspec.
- The -S option causes
gprofto read an external symbol table file, such as /proc/kallsyms, rather than read the symbol table from the given object file (the default is
a.out). This is useful for profiling kernel modules.
- If you give the -z option,
gprofwill mention all functions in the flat profile, even those that were never called, and that had no time spent in them. This is useful in conjunction with the -c option for discovering which routines were never called.