1memusage(1)                 General Commands Manual                memusage(1)
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NAME

6       memusage - profile memory usage of a program
7

SYNOPSIS

9       memusage [option]... program [programoption]...
10

DESCRIPTION

12       memusage  is  a bash script which profiles memory usage of the program,
13       program.  It preloads the libmemusage.so library into the caller's  en‐
14       vironment (via the LD_PRELOAD environment variable; see ld.so(8)).  The
15       libmemusage.so library traces memory allocation by  intercepting  calls
16       to  malloc(3), calloc(3), free(3), and realloc(3); optionally, calls to
17       mmap(2), mremap(2), and munmap(2) can also be intercepted.
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19       memusage can output the collected data in textual form, or it  can  use
20       memusagestat(1)  (see  the -p option,  below) to create a PNG file con‐
21       taining graphical representation of the collected data.
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23   Memory usage summary
24       The "Memory usage summary"  line  output  by  memusage  contains  three
25       fields:
26
27           heap total
28                  Sum  of  size  arguments of all malloc(3) calls, products of
29                  arguments (nmemb*size) of all calloc(3) calls,  and  sum  of
30                  length arguments of all mmap(2) calls.  In the case of real‐
31                  loc(3) and mremap(2), if the new size of  an  allocation  is
32                  larger  than  the previous size, the sum of all such differ‐
33                  ences (new size minus old size) is added.
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35           heap peak
36                  Maximum of all size arguments of malloc(3), all products  of
37                  nmemb*size  of  calloc(3), all size arguments of realloc(3),
38                  length arguments  of  mmap(2),  and  new_size  arguments  of
39                  mremap(2).
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41           stack peak
42                  Before  the  first call to any monitored function, the stack
43                  pointer address (base stack pointer) is saved.   After  each
44                  function  call, the actual stack pointer address is read and
45                  the difference from the base stack  pointer  computed.   The
46                  maximum of these differences is then the stack peak.
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48       Immediately  following  this  summary  line,  a  table shows the number
49       calls, total memory allocated or  deallocated,  and  number  of  failed
50       calls for each intercepted function.  For realloc(3) and mremap(2), the
51       additional field "nomove" shows reallocations that changed the  address
52       of a block, and the additional "dec" field shows reallocations that de‐
53       creased the size of the block.  For realloc(3),  the  additional  field
54       "free"  shows  reallocations that caused a block to be freed (i.e., the
55       reallocated size was 0).
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57       The "realloc/total memory" of the table output by memusage does not re‐
58       flect cases where realloc(3) is used to reallocate a block of memory to
59       have a smaller size than previously.  This can cause sum of all  "total
60       memory" cells (excluding "free") to be larger than the "free/total mem‐
61       ory" cell.
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63   Histogram for block sizes
64       The "Histogram for block sizes" provides a breakdown of memory  alloca‐
65       tions into various bucket sizes.
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OPTIONS

68       -n name, --progname=name
69              Name of the program file to profile.
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71       -p file, --png=file
72              Generate PNG graphic and store it in file.
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74       -d file, --data=file
75              Generate binary data file and store it in file.
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77       -u, --unbuffered
78              Do not buffer output.
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80       -b size, --buffer=size
81              Collect size entries before writing them out.
82
83       --no-timer
84              Disable timer-based (SIGPROF) sampling of stack pointer value.
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86       -m, --mmap
87              Also trace mmap(2), mremap(2), and munmap(2).
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89       -?, --help
90              Print help and exit.
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92       --usage
93              Print a short usage message and exit.
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95       -V, --version
96              Print version information and exit.
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98       The following options apply only when generating graphical output:
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100       -t, --time-based
101              Use time (rather than number of function calls) as the scale for
102              the X axis.
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104       -T, --total
105              Also draw a graph of total memory use.
106
107       --title=name
108              Use name as the title of the graph.
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110       -x size, --x-size=size
111              Make the graph size pixels wide.
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113       -y size, --y-size=size
114              Make the graph size pixels high.
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EXIT STATUS

117       The exit status of memusage is equal to the exit status of the profiled
118       program.
119

BUGS

121       To report bugs, see ⟨http://www.gnu.org/software/libc/bugs.html
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EXAMPLES

124       Below  is a simple program that reallocates a block of memory in cycles
125       that rise to a peak before then cyclically reallocating the  memory  in
126       smaller  blocks  that  return to zero.  After compiling the program and
127       running the following commands, a graph of the memory usage of the pro‐
128       gram can be found in the file memusage.png:
129
130           $ memusage --data=memusage.dat ./a.out
131           ...
132           Memory usage summary: heap total: 45200, heap peak: 6440, stack peak: 224
133                   total calls  total memory  failed calls
134            malloc|         1           400             0
135           realloc|        40         44800             0  (nomove:40, dec:19, free:0)
136            calloc|         0             0             0
137              free|         1           440
138           Histogram for block sizes:
139             192-207             1   2% ================
140           ...
141            2192-2207            1   2% ================
142            2240-2255            2   4% =================================
143            2832-2847            2   4% =================================
144            3440-3455            2   4% =================================
145            4032-4047            2   4% =================================
146            4640-4655            2   4% =================================
147            5232-5247            2   4% =================================
148            5840-5855            2   4% =================================
149            6432-6447            1   2% ================
150           $ memusagestat memusage.dat memusage.png
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152   Program source
153       #include <stdio.h>
154       #include <stdlib.h>
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156       #define CYCLES 20
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158       int
159       main(int argc, char *argv[])
160       {
161           int i, j;
162           size_t size;
163           int *p;
164
165           size = sizeof(*p) * 100;
166           printf("malloc: %zu\n", size);
167           p = malloc(size);
168
169           for (i = 0; i < CYCLES; i++) {
170               if (i < CYCLES / 2)
171                   j = i;
172               else
173                   j--;
174
175               size = sizeof(*p) * (j * 50 + 110);
176               printf("realloc: %zu\n", size);
177               p = realloc(p, size);
178
179               size = sizeof(*p) * ((j + 1) * 150 + 110);
180               printf("realloc: %zu\n", size);
181               p = realloc(p, size);
182           }
183
184           free(p);
185           exit(EXIT_SUCCESS);
186       }
187

SEE ALSO

189       memusagestat(1), mtrace(1), ld.so(8)
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193Linux man-pages 6.04              2023-01-07                       memusage(1)
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