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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | EXIT STATUS | BUGS | EXAMPLE | SEE ALSO | COLOPHON |
MEMUSAGE(1) Linux user manual MEMUSAGE(1)
memusage - profile memory usage of a program
memusage [option]... program [programoption]...
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.
-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 is equal to the exit status of profiled program.
To report bugs, see ⟨http://www.gnu.org/software/libc/bugs.html⟩
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);
}
memusagestat(1), mtrace(1) ld.so(8)
This page is part of release 4.12 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 2016-10-08 MEMUSAGE(1)
Pages that refer to this page: memusagestat(1), mtrace(1)