sprof(1)



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  <son-
       ame>.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 con-
       sists 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 profiling
       data:

           $ rm -f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile

       We then run the program to produce the profiling output, which is writ-
       ten 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 4.14 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)

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