sprof Man page

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 .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

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

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
[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, ldd, 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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