memusage - Online Linux Manual PageSection : 1
Updated : 2023-01-07
Source : Linux man-pages 6.03
NAMEmemusage − profile memory usage of a program
SYNOPSISmemusage [option]... program [programoption]...
DESCRIPTIONmemusage 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 summaryThe "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 sizesThe "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 STATUSThe exit status of memusage is equal to the exit status of the profiled program.
BUGSTo report bugs, see http://www.gnu.org/software/libc/bugs.html
EXAMPLESBelow 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 ALSOmemusagestat(1), mtrace(1), ld.so(8) 0
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