sprof (1)
Leading comments
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. ...
NAME
sprof - read and display shared object profiling dataSYNOPSIS
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 <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.EXAMPLE
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) { 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 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