MEMUSAGE
Section: Linux user manual (1)
Updated: 2017-09-15
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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
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
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/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- Memory usage summary
-
- Histogram for block sizes
-
- OPTIONS
-
- EXIT STATUS
-
- BUGS
-
- EXAMPLE
-
- Program source
-
- SEE ALSO
-
- COLOPHON
-
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