memusage(1) — Linux manual page

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | BUGS | EXAMPLES | SEE ALSO | COLOPHON

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 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         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.

       --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         top

       The exit status of memusage is equal to the exit status of the
       profiled program.

BUGS         top

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

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

       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         top

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

COLOPHON         top

       This page is part of release 5.12 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                            2021-03-22                    MEMUSAGE(1)

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