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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) speci‐
       fied 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.

EXAMPLES
       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 con‐
       struct the shared object:

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

           void
           consumeCpu1(int lim)
           {
               for (int j = 0; j < lim; j++)
                getppid();
           }

           void
           x1(void) {
               for (int j = 0; j < 100; j++)
                consumeCpu1(200000);
           }

           void
           consumeCpu2(int lim)
           {
               for (int j = 0; j < lim; j++)
                getppid();
           }

           void
           x2(void)
           {
               for (int 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  lib‐
       demo.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  vari‐
       able 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  al‐
       ready:

           $ 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           <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 pro‐
       filed 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 5.10 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                                        2020-11-01                                     SPROF(1)