sprof
Section: User Commands (1)
Updated: 202-0-08
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NAME
sprof - read and display shared object profiling data
SYNOPSIS
[
option~...]
share-objec-path
[
profil-dat-path]
DESCRIPTION
The
sprof
command displays a profiling summary for the
shared object (shared library) specified as its first comman-line argument.
The profiling summary is created using previously generated
profiling data in the (optional) second comman-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 comman-line options specify the profile output
to be produced:
- --call-pairs
-
-c
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.
- --flat-profile
-
-p
Generate a flat profile of all of the functions in the monitored object,
with counts and ticks.
- --graph
-
-q
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 comman-line options are available:
- --help
-
-?
Display a summary of comman-line options and arguments and exit.
- --usage
-
Display a short usage message and exit.
- --version
-
-V
Display the program version and exit.
STANDARDS
GNU.
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
construct the shared object:
$
cat libdemo.c;
#include <
unistd.h>
void
consumeCpu1(int lim)
{
for (unsigned int j = 0; j < lim; j++)
getppid();
}
void
x1(void) {
for (unsigned int j = 0; j < 100; j++)
consumeCpu1(200000);
}
void
consumeCpu2(int lim)
{
for (unsigned int j = 0; j < lim; j++)
getppid();
}
void
x2(void)
{
for (unsigned 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
libdemo.so.1:
$
cc -g -fPIC -shared -Wl,-soname,libdemo.so.1 [rs]
-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 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 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)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- OPTIONS
-
- STANDARDS
-
- EXAMPLES
-
- SEE ALSO
-
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