.\" Copyright (C) 2014 Michael Kerrisk <mtk.manpages@gmail.com>
.\"
.\" %%%LICENSE_START(VERBATIM)
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" %%%LICENSE_END
.\"
.TH SPROF 1 2017-09-15 "Linux" "Linux User Manual"
.SH NAME
sprof \- read and display shared object profiling data
.SH SYNOPSIS
.nf
.BR sprof " [\fIoption\fP]... \fIshared-object-path\fP \
[\fIprofile-data-path\fP]"
.fi
.SH DESCRIPTION
The
.B 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
.B sprof
will attempt to deduce it using the soname of the shared object,
looking for a file with the name
.IR <soname>.profile
in the current directory.
.SH OPTIONS
The following command-line options specify the profile output
to be produced:
.TP
.BR \-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.
.TP
.BR \-p ", " \-\-flat\-profile
Generate a flat profile of all of the functions in the monitored object,
with counts and ticks.
.TP
.BR \-q ", " \-\-graph
Generate a call graph.
.PP
If none of the above options is specified,
then the default behavior is to display a flat profile and a call graph.
.PP
The following additional command-line options are available:
.TP
.BR \-? ", " \-\-help
Display a summary of command-line options and arguments and exit.
.TP
.BR \-\-usage
Display a short usage message and exit.
.TP
.BR \-V ", " \-\-version
Display the program version and exit.
.SH CONFORMING TO
The
.B sprof
command is a GNU extension, not present in POSIX.1.
.SH EXAMPLE
The following example demonstrates the use of
.BR sprof .
The example consists of a main program that calls two functions
in a shared object.
First, the code of the main program:
.PP
.in +4n
.EX
$ \fBcat prog.c\fP
#include <stdlib.h>

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

int
main(int argc, char *argv[])
{
    x1();
    x2();
    exit(EXIT_SUCCESS);
}
.EE
.in
.PP
The functions
.IR x1()
and
.IR x2()
are defined in the following source file that is used to
construct the shared object:
.PP
.in +4n
.EX
$ \fBcat libdemo.c\fP
#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);
}
.EE
.in
.PP
Now we construct the shared object with the real name
.IR libdemo.so.1.0.1 ,
and the soname
.IR libdemo.so.1 :
.PP
.in +4n
.EX
$ \fBcc \-g \-fPIC \-shared \-Wl,\-soname,libdemo.so.1 \e\fP
        \fB\-o libdemo.so.1.0.1 libdemo.c\fP
.EE
.in
.PP
Then we construct symbolic links for the library soname and
the library linker name:
.PP
.in +4n
.EX
$ \fBln \-sf libdemo.so.1.0.1 libdemo.so.1\fP
$ \fBln \-sf libdemo.so.1 libdemo.so\fP
.EE
.in
.PP
Next, we compile the main program, linking it against the shared object,
and then list the dynamic dependencies of the program:
.PP
.in +4n
.EX
$ \fBcc \-g \-o prog prog.c \-L. \-ldemo\fP
$ \fBldd prog\fP
	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)
.EE
.in
.PP
In order to get profiling information for the shared object,
we define the environment variable
.BR LD_PROFILE
with the soname of the library:
.PP
.in +4n
.EX
$ \fBexport LD_PROFILE=libdemo.so.1\fP
.EE
.in
.PP
We then define the environment variable
.BR 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:
.PP
.in +4n
.EX
$ \fBexport LD_PROFILE_OUTPUT=$(pwd)/prof_data\fP
$ \fBmkdir \-p $LD_PROFILE_OUTPUT\fP
.EE
.in
.PP
.B LD_PROFILE
causes profiling output to be
.I appended
to the output file if it already exists,
so we ensure that there is no preexisting profiling data:
.PP
.in +4n
.EX
$ \fBrm \-f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile\fP
.EE
.in
.PP
We then run the program to produce the profiling output,
which is written to a file in the directory specified in
.BR LD_PROFILE_OUTPUT :
.PP
.in +4n
.EX
$ \fBLD_LIBRARY_PATH=. ./prog\fP
$ \fBls prof_data\fP
libdemo.so.1.profile
.EE
.in
.PP
We then use the
.BR "sprof \-p"
option to generate a flat profile with counts and ticks:
.PP
.in +4n
.EX
$ \fBsprof \-p libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
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
.EE
.in
.PP
The
.BR "sprof \-q"
option generates a call graph:
.PP
.in +4n
.EX
$ \fBsprof \-q libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP

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]
\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-\-
.EE
.in
.PP
Above and below, the "<UNKNOWN>" strings represent identifiers that
are outside of the profiled object (in this example, these are instances of
.IR main() ).
.PP
The
.BR "sprof \-c"
option generates a list of call pairs and the number of their occurrences:
.PP
.in +4n
.EX
$ \fBsprof \-c libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile\fP
<UNKNOWN>                  x1                                 1
x1                         consumeCpu1                      100
<UNKNOWN>                  x2                                 1
x2                         consumeCpu2                     1000
.EE
.in
.SH SEE ALSO
.BR gprof (1),
.BR ldd (1),
.BR ld.so (8)
.SH COLOPHON
This page is part of release 4.16 of the Linux
.I 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/.