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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 pre‐
       viously  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 .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 pro‐
       gram that calls two functions in a shared object.  First, the code of the main program:

           $ cat prog.c
           #include 

           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  con‐
       struct the shared object:

           $ cat libdemo.c
           #include 

           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  direc‐
       tory  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 profiling 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           
           [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           
           [3]      0.0    0.00    0.00        1         x2 [3]
                           0.00    0.00     1000/1000        consumeCpu2 [2]
           -----------------------------------------------

       Above and below, the "" 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
                             x1                                 1
           x1                         consumeCpu1                      100
                             x2                                 1
           x2                         consumeCpu2                     1000

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

COLOPHON
       This  page  is  part of release 4.04 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 http://www.kernel.org/doc/man-pages/.

Linux                                       2015-08-08                                   SPROF(1)

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