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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 containing graphical representation of  the  col‐
       lected 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 cal‐‐
                  loc(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  ad‐
                  dress  is read and the difference from the base stack pointer computed.  The maxi‐
                  mum of these differences is then the stack peak.

       Immediately following this summary line, a table shows the number calls, total  memory  allo‐
       cated  or  deallocated,  and number of failed calls for each intercepted function.  For real‐‐
       loc(3) and mremap(2), the additional field "nomove" shows reallocations that changed the  ad‐
       dress  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 real‐‐
       loc(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/to‐
       tal 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⟩

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 5.10 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                                          2020-11-01                                  MEMUSAGE(1)