sprof.1 - Online Linux Manual Page

sprof - Online Linux Manual PageSection : 1
Updated : 2023-01-07
Source : Linux man-pages 6.03

NAMEsprof − read and display shared object profiling data

SYNOPSISsprof [option]... shared-object-path [profile-data-path]

DESCRIPTIONThe 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.

OPTIONSThe 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.

STANDARDSThe sprof command is a GNU extension, not present in POSIX.1.

EXAMPLESThe 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 \ −o libdemo.so.1.0.1 libdemo.cThen 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.soNext, 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.1We 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_OUTPUTLD_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.profileWe 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.profileWe 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 x2The 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