memusage(1) — Linux manual page


MEMUSAGE(1)                   Linux user manual                  MEMUSAGE(1)

NAME         top

       memusage - profile memory usage of a program

SYNOPSIS         top

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

DESCRIPTION         top

       memusage is a bash script which profiles memory usage of the program,
       program.  It preloads the library into the caller's
       environment (via the LD_PRELOAD environment variable; see
       The 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

           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         top

       -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.

              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.

              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.

              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         top

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

BUGS         top

       To report bugs, see ⟨

EXAMPLES         top

       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

       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;

                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));


SEE ALSO         top

       memusagestat(1), mtrace(1),

COLOPHON         top

       This page is part of release 5.08 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

GNU                              2020-06-09                      MEMUSAGE(1)

Pages that refer to this page: memusagestat(1)mtrace(1)