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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.

BUGS

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

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);
       }

SEE ALSO

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

COLOPHON

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       project,  information  about  reporting  bugs, and the latest version of this page, can be
       found at https://www.kernel.org/doc/man-pages/.