SPROF(1)							 Linux User Manual							  SPROF(1)

NAME

       sprof - read and display shared object profiling data

SYNOPSIS

       sprof [option]... shared-object-path [profile-data-path]

DESCRIPTION

       The  sprof  command  displays a profiling summary for the shared object (shared library) specified as its first command-line argument.  The
       profiling summary is created using previously generated profiling data in the (optional) second command-line argument.	If  the  profiling
       data  pathname  is  omitted,  then  sprof will attempt to deduce it using the soname of the shared object, looking for a file with the name
       <soname>.profile in the current directory.

OPTIONS

       The following command-line options specify the profile output to be produced:

       -c, --call-pairs
	      Print a list of pairs of call paths for the interfaces exported by the shared object, along with the number of times  each  path	is
	      used.

       -p, --flat-profile
	      Generate a flat profile of all of the functions in the monitored object, with counts and ticks.

       -q, --graph
	      Generate a call graph.

       If none of the above options is specified, then the default behavior is to display a flat profile and a call graph.

       The following additional command-line options are available:

       -?, --help
	      Display a summary of command-line options and arguments and exit.

       --usage
	      Display a short usage message and exit.

       -V, --version
	      Display the program version and exit.

CONFORMING TO

       The sprof command is a GNU extension, not present in POSIX.1.

EXAMPLE

       The  following  example demonstrates the use of sprof.  The example consists of a main program that calls two functions in a shared object.
       First, the code of the main program:

	   $ cat prog.c
	   #include <stdlib.h>

	   void x1(void);
	   void x2(void);

	   int
	   main(int argc, char *argv[])
	   {
	       x1();
	       x2();
	       exit(EXIT_SUCCESS);
	   }

       The functions x1() and x2() are defined in the following source file that is used to construct the shared object:

	   $ cat libdemo.c
	   #include <unistd.h>

	   void
	   consumeCpu1(int lim)
	   {
	       int j;

	       for (j = 0; j < lim; j++)
		getppid();
	   }

	   void
	   x1(void) {
	       int j;

	       for (j = 0; j < 100; j++)
		consumeCpu1(200000);
	   }

	   void
	   consumeCpu2(int lim)
	   {
	       int j;

	       for (j = 0; j < lim; j++)
		getppid();
	   }

	   void
	   x2(void)
	   {
	       int j;

	       for (j = 0; j < 1000; j++)
		consumeCpu2(10000);
	   }

       Now we construct the shared object with the real name libdemo.so.1.0.1, and the soname libdemo.so.1:

	   $ cc -g -fPIC -shared -Wl,-soname,libdemo.so.1 
		   -o libdemo.so.1.0.1 libdemo.c

       Then we construct symbolic links for the library soname and the library linker name:

	   $ ln -sf libdemo.so.1.0.1 libdemo.so.1
	   $ ln -sf libdemo.so.1 libdemo.so

       Next, we compile the main program, linking it against the shared object, and then list the dynamic dependencies of the program:

	   $ cc -g -o prog prog.c -L. -ldemo
	   $ ldd prog
		linux-vdso.so.1 =>  (0x00007fff86d66000)
		libdemo.so.1 => not found
		libc.so.6 => /lib64/libc.so.6(0x00007fd4dc138000)
		/lib64/ld-linux-x86-64.so.2(0x00007fd4dc51f000)

       In order to get profiling information for the shared object, we define the environment variable LD_PROFILE with the soname of the library:

	   $ export LD_PROFILE=libdemo.so.1

       We then define the environment variable LD_PROFILE_OUTPUT with the pathname of the directory where profile output should  be  written,  and
       create that directory if it does not exist already:

	   $ export LD_PROFILE_OUTPUT=$(pwd)/prof_data
	   $ mkdir -p $LD_PROFILE_OUTPUT

       LD_PROFILE  causes  profiling output to be appended to the output file if it already exists, so we ensure that there is no preexisting pro-
       filing data:

	   $ rm -f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile

       We then run the program to produce the profiling output, which is written to a file in the directory specified in LD_PROFILE_OUTPUT:

	   $ LD_LIBRARY_PATH=. ./prog
	   $ ls prof_data
	   libdemo.so.1.profile

       We then use the sprof -p option to generate a flat profile with counts and ticks:

	   $ sprof -p libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile
	   Flat profile:

	   Each sample counts as 0.01 seconds.
	     %	 cumulative   self		self	 total
	    time   seconds   seconds	calls  us/call	us/call  name
	    60.00      0.06	0.06	  100	600.00		 consumeCpu1
	    40.00      0.10	0.04	 1000	 40.00		 consumeCpu2
	     0.00      0.10	0.00	    1	  0.00		 x1
	     0.00      0.10	0.00	    1	  0.00		 x2

       The sprof -q option generates a call graph:

	   $ sprof -q libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile

	   index % time    self  children    called	name

			   0.00    0.00      100/100	     x1 [1]
	   [0]	  100.0    0.00    0.00      100	 consumeCpu1 [0]
	   -----------------------------------------------
			   0.00    0.00        1/1	     <UNKNOWN>
	   [1]	    0.0    0.00    0.00        1	 x1 [1]
			   0.00    0.00      100/100	     consumeCpu1 [0]
	   -----------------------------------------------
			   0.00    0.00     1000/1000	     x2 [3]
	   [2]	    0.0    0.00    0.00     1000	 consumeCpu2 [2]
	   -----------------------------------------------
			   0.00    0.00        1/1	     <UNKNOWN>
	   [3]	    0.0    0.00    0.00        1	 x2 [3]
			   0.00    0.00     1000/1000	     consumeCpu2 [2]
	   -----------------------------------------------

       Above and below, the "<UNKNOWN>" strings represent identifiers that are outside	of  the  profiled  object  (in	this  example,	these  are
       instances of main()).

       The sprof -c option generates a list of call pairs and the number of their occurrences:

	   $ sprof -c libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile
	   <UNKNOWN>		      x1				 1
	   x1			      consumeCpu1		       100
	   <UNKNOWN>		      x2				 1
	   x2			      consumeCpu2		      1000

SEE ALSO

       gprof(1), ldd(1), ld.so(8)

COLOPHON

       This  page is part of release 4.15 of the Linux man-pages project.  A description of the project, information about reporting bugs, and the
       latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Linux								    2017-09-15								  SPROF(1)