Manpages - memusage.1

Table of Contents

NAME

memusage - profile memory usage of a program

SYNOPSIS

  memusage [option]... program [programoption]...

DESCRIPTION

memusage is a bash script which profiles memory usage of the program, program. It preloads the libmemusage.so library into the caller’s environment (via the LD_PRELOAD environment variable; see ld.so*(8)). The *libmemusage.so library traces memory allocation by intercepting calls to *malloc*(3), *calloc*(3), *free*(3), and *realloc*(3); optionally, calls to *mmap*(2), *mremap*(2), and *munmap*(2) can also be intercepted.

memusage can output the collected data in textual form, or it can use memusagestat*(1) (see the *-p option, below) to create a PNG file containing graphical representation of the collected data.

Memory usage summary

The “Memory usage summary” line output by memusage contains three fields:

heap total
Sum of size arguments of all *malloc*(3) calls, products of arguments (nmemb/*/size) of all *calloc*(3) calls, and sum of length arguments of all *mmap*(2) calls. In the case of *realloc*(3) and *mremap*(2), if the new size of an allocation is larger than the previous size, the sum of all such differences (new size minus old size) is added.
heap peak
Maximum of all size arguments of *malloc*(3), all products of nmemb/*/size of *calloc*(3), all size arguments of *realloc*(3), length arguments of *mmap*(2), and new_size arguments of *mremap*(2).
stack peak
Before the first call to any monitored function, the stack pointer address (base stack pointer) is saved. After each function call, the actual stack pointer address is read and the difference from the base stack pointer computed. The maximum of these differences is then the stack peak.

Immediately following this summary line, a table shows the number calls, total memory allocated or deallocated, and number of failed calls for each intercepted function. For *realloc*(3) and *mremap*(2), the additional field “nomove” shows reallocations that changed the address of a block, and the additional “dec” field shows reallocations that decreased the size of the block. For *realloc*(3), the additional field “free” shows reallocations that caused a block to be freed (i.e., the reallocated size was 0).

The “realloc/total memory” of the table output by memusage does not reflect cases where *realloc*(3) is used to reallocate a block of memory to have a smaller size than previously. This can cause sum of all “total memory” cells (excluding “free”) to be larger than the “free/total memory” cell.

Histogram for block sizes

The “Histogram for block sizes” provides a breakdown of memory allocations into various bucket sizes.

OPTIONS

-n */name/, *–progname=**/name/
Name of the program file to profile.
-p */file/, *–png=**/file/
Generate PNG graphic and store it in file.
-d */file/, *–data=**/file/
Generate binary data file and store it in file.
-u, –unbuffered
Do not buffer output.
-b */size/, *–buffer=**/size/
Collect size entries before writing them out.
–no-timer
Disable timer-based (SIGPROF) sampling of stack pointer value.
-m, –mmap
Also trace *mmap*(2), *mremap*(2), and *munmap*(2).
-?, –help
Print help and exit.
–usage
Print a short usage message and exit.
-V, –version
Print version information and exit.
The following options apply only when generating graphical output:
-t, –time-based
Use time (rather than number of function calls) as the scale for the X axis.
-T, –total
Also draw a graph of total memory use.
**–title=**/name/
Use name as the title of the graph.
-x */size/, *–x-size=**/size/
Make the graph size pixels wide.
-y */size/, *–y-size=**/size/
Make the graph size pixels high.

EXIT STATUS

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

BUGS

To report bugs, see [[http://www.gnu.org/software/libc/bugs.html][]]

EXAMPLES

Below is a simple program that reallocates a block of memory in cycles that rise to a peak before then cyclically reallocating the memory in smaller blocks that return to zero. After compiling the program and running the following commands, a graph of the memory usage of the program can be found in the file memusage.png:

  $ memusage --data=memusage.dat ./a.out
  ...
  Memory usage summary: heap total: 45200, heap peak: 6440, stack peak: 224
          total calls  total memory  failed calls
   malloc|         1           400             0
  realloc|        40         44800             0  (nomove:40, dec:19, free:0)
   calloc|         0             0             0
     free|         1           440
  Histogram for block sizes:
    192-207             1   2% ================
  ...
   2192-2207            1   2% ================
   2240-2255            2   4% =================================
   2832-2847            2   4% =================================
   3440-3455            2   4% =================================
   4032-4047            2   4% =================================
   4640-4655            2   4% =================================
   5232-5247            2   4% =================================
   5840-5855            2   4% =================================
   6432-6447            1   2% ================
  $ memusagestat memusage.dat memusage.png

Program source

  #include <stdio.h>
  #include <stdlib.h>

  #define CYCLES 20

  int
  main(int argc, char *argv[])
  {
      int i, j;
      size_t size;
      int *p;

      size = sizeof(*p) * 100;
      printf("malloc: %zu\n", size);
      p = malloc(size);

      for (i = 0; i < CYCLES; i++) {
          if (i < CYCLES / 2)
              j = i;
          else
              j--;

          size = sizeof(*p) * (j * 50 + 110);
          printf("realloc: %zu\n", size);
          p = realloc(p, size);

          size = sizeof(*p) * ((j + 1) * 150 + 110);
          printf("realloc: %zu\n", size);
          p = realloc(p, size);
      }

      free(p);
      exit(EXIT_SUCCESS);
  }

SEE ALSO

*memusagestat*(1), *mtrace*(1), *ld.so*(8)

COLOPHON

This page is part of release 5.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.

Information about memusage.1 is found in manpage for: ld.so (8)). ld.so (8)

Author: dt

Created: 2022-02-22 Tue 16:54