MEMUSAGE(1)

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
Exit status is equal to the exit status of profiled program.

EXAMPLE
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;
     int *p;
     printf("malloc: %zd\n", sizeof(int) * 100);
     p = malloc(sizeof(int) * 100);
     for (i = 0; i < CYCLES; i++) {
         if (i < CYCLES / 2)
             j = i;
         else
             j--;
         printf("realloc: %zd\n", sizeof(int) * (j * 50 + 110));
         p = realloc(p, sizeof(int) * (j * 50 + 100));
         printf("realloc: %zd\n", sizeof(int) * ((j+1) * 150 + 110));
         p = realloc(p, sizeof(int) * ((j + 1) * 150 + 110));
     }
     free(p);
     exit(EXIT_SUCCESS);
}

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

SEE ALSO
memusagestat(1), mtrace(1) ld.so(8)

COLOPHON
This page is part of release 4.04 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 http://www.kernel.org/doc/man-pages/.