1SPROF(1)                       Linux User Manual                      SPROF(1)
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NAME

6       sprof - read and display shared object profiling data
7

SYNOPSIS

9       sprof [option]... shared-object-path [profile-data-path]
10

DESCRIPTION

12       The  sprof  command  displays a profiling summary for the shared object
13       (shared library) specified as its  first  command-line  argument.   The
14       profiling  summary is created using previously generated profiling data
15       in the (optional) second command-line argument.  If the profiling  data
16       pathname  is  omitted,  then  sprof will attempt to deduce it using the
17       soname of the shared object, looking for a file  with  the  name  <son‐
18       ame>.profile in the current directory.
19

OPTIONS

21       The  following  command-line  options  specify the profile output to be
22       produced:
23
24       -c, --call-pairs
25              Print a list of pairs of call paths for the interfaces  exported
26              by  the  shared object, along with the number of times each path
27              is used.
28
29       -p, --flat-profile
30              Generate a flat profile of all of the functions in the monitored
31              object, with counts and ticks.
32
33       -q, --graph
34              Generate a call graph.
35
36       If none of the above options is specified, then the default behavior is
37       to display a flat profile and a call graph.
38
39       The following additional command-line options are available:
40
41       -?, --help
42              Display a summary of  command-line  options  and  arguments  and
43              exit.
44
45       --usage
46              Display a short usage message and exit.
47
48       -V, --version
49              Display the program version and exit.
50

CONFORMING TO

52       The sprof command is a GNU extension, not present in POSIX.1.
53

EXAMPLE

55       The  following example demonstrates the use of sprof.  The example con‐
56       sists of a main program that calls two functions in  a  shared  object.
57       First, the code of the main program:
58
59           $ cat prog.c
60           #include <stdlib.h>
61
62           void x1(void);
63           void x2(void);
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65           int
66           main(int argc, char *argv[])
67           {
68               x1();
69               x2();
70               exit(EXIT_SUCCESS);
71           }
72
73       The  functions  x1()  and x2() are defined in the following source file
74       that is used to construct the shared object:
75
76           $ cat libdemo.c
77           #include <unistd.h>
78
79           void
80           consumeCpu1(int lim)
81           {
82               int j;
83
84               for (j = 0; j < lim; j++)
85                getppid();
86           }
87
88           void
89           x1(void) {
90               int j;
91
92               for (j = 0; j < 100; j++)
93                consumeCpu1(200000);
94           }
95
96           void
97           consumeCpu2(int lim)
98           {
99               int j;
100
101               for (j = 0; j < lim; j++)
102                getppid();
103           }
104
105           void
106           x2(void)
107           {
108               int j;
109
110               for (j = 0; j < 1000; j++)
111                consumeCpu2(10000);
112           }
113
114       Now we construct the shared object with the real name libdemo.so.1.0.1,
115       and the soname libdemo.so.1:
116
117           $ cc -g -fPIC -shared -Wl,-soname,libdemo.so.1 \
118                   -o libdemo.so.1.0.1 libdemo.c
119
120       Then we construct symbolic links for the library soname and the library
121       linker name:
122
123           $ ln -sf libdemo.so.1.0.1 libdemo.so.1
124           $ ln -sf libdemo.so.1 libdemo.so
125
126       Next, we compile the  main  program,  linking  it  against  the  shared
127       object, and then list the dynamic dependencies of the program:
128
129           $ cc -g -o prog prog.c -L. -ldemo
130           $ ldd prog
131                linux-vdso.so.1 =>  (0x00007fff86d66000)
132                libdemo.so.1 => not found
133                libc.so.6 => /lib64/libc.so.6 (0x00007fd4dc138000)
134                /lib64/ld-linux-x86-64.so.2 (0x00007fd4dc51f000)
135
136       In  order to get profiling information for the shared object, we define
137       the environment variable LD_PROFILE with the soname of the library:
138
139           $ export LD_PROFILE=libdemo.so.1
140
141       We then define the  environment  variable  LD_PROFILE_OUTPUT  with  the
142       pathname  of  the directory where profile output should be written, and
143       create that directory if it does not exist already:
144
145           $ export LD_PROFILE_OUTPUT=$(pwd)/prof_data
146           $ mkdir -p $LD_PROFILE_OUTPUT
147
148       LD_PROFILE causes profiling output to be appended to the output file if
149       it  already exists, so we ensure that there is no preexisting profiling
150       data:
151
152           $ rm -f $LD_PROFILE_OUTPUT/$LD_PROFILE.profile
153
154       We then run the program to produce the profiling output, which is writ‐
155       ten to a file in the directory specified in LD_PROFILE_OUTPUT:
156
157           $ LD_LIBRARY_PATH=. ./prog
158           $ ls prof_data
159           libdemo.so.1.profile
160
161       We  then use the sprof -p option to generate a flat profile with counts
162       and ticks:
163
164           $ sprof -p libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile
165           Flat profile:
166
167           Each sample counts as 0.01 seconds.
168             %   cumulative   self              self     total
169            time   seconds   seconds    calls  us/call  us/call  name
170            60.00      0.06     0.06      100   600.00           consumeCpu1
171            40.00      0.10     0.04     1000    40.00           consumeCpu2
172             0.00      0.10     0.00        1     0.00           x1
173             0.00      0.10     0.00        1     0.00           x2
174
175       The sprof -q option generates a call graph:
176
177           $ sprof -q libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile
178
179           index % time    self  children    called     name
180
181                           0.00    0.00      100/100         x1 [1]
182           [0]    100.0    0.00    0.00      100         consumeCpu1 [0]
183           -----------------------------------------------
184                           0.00    0.00        1/1           <UNKNOWN>
185           [1]      0.0    0.00    0.00        1         x1 [1]
186                           0.00    0.00      100/100         consumeCpu1 [0]
187           -----------------------------------------------
188                           0.00    0.00     1000/1000        x2 [3]
189           [2]      0.0    0.00    0.00     1000         consumeCpu2 [2]
190           -----------------------------------------------
191                           0.00    0.00        1/1           <UNKNOWN>
192           [3]      0.0    0.00    0.00        1         x2 [3]
193                           0.00    0.00     1000/1000        consumeCpu2 [2]
194           -----------------------------------------------
195
196       Above and below, the "<UNKNOWN>" strings represent identifiers that are
197       outside of the profiled object (in this example, these are instances of
198       main()).
199
200       The sprof -c option generates a list of call pairs and  the  number  of
201       their occurrences:
202
203           $ sprof -c libdemo.so.1 $LD_PROFILE_OUTPUT/libdemo.so.1.profile
204           <UNKNOWN>                  x1                                 1
205           x1                         consumeCpu1                      100
206           <UNKNOWN>                  x2                                 1
207           x2                         consumeCpu2                     1000
208

SEE ALSO

210       gprof(1), ldd(1), ld.so(8)
211

COLOPHON

213       This  page  is  part of release 5.02 of the Linux man-pages project.  A
214       description of the project, information about reporting bugs,  and  the
215       latest     version     of     this    page,    can    be    found    at
216       https://www.kernel.org/doc/man-pages/.
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220Linux                             2019-03-06                          SPROF(1)
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