memusage(1)



MEMUSAGE(1)                    Linux user manual                   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 con-
       taining 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 real-
                  loc(3) and mremap(2), if the new size of  an  allocation  is
                  larger  than  the previous size, the sum of all such differ-
                  ences (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  alloca-
       tions 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 pro-
       gram 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
       This page is part of release 4.13 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/.

GNU                               2017-09-15                       MEMUSAGE(1)

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