OSTEP chappter 13 homework
1
This is the output of man free in AWS EC2. man free result in macOS is different.
FREE(1) Linux User's Manual FREE(1)
NAME
free - Display amount of free and used memory in the system
SYNOPSIS
free [-b | -k | -m | -g | -h] [-o] [-s delay ] [-c count ] [-a] [-t] [-l] [-V]
DESCRIPTION
free displays the total amount of free and used physical and swap memory in the system, as well as the buffers used by the kernel. The shared memory column represents the 'Shmem' value. The available memory column represents the 'MemAvailable' value.
Options
The -b switch displays the amount of memory in bytes; the -k switch (set by default) displays it in kilobytes; the -m switch displays it in megabytes; the -g switch displays it in gigabytes.
The -h switch displays all output fields automatically scaled to the shortest (three digit) representation including the unit. That makes the values human readable.
The -t switch displays a line containing the totals.
The -o switch disables the display of a "buffer adjusted" line. If the -o option is not specified, free subtracts buffer memory from the used memory and adds it to the free memory reported.
The -s switch activates continuous polling delay seconds apart. You may actually specify any floating point number for delay, usleep(3) is used for microsecond resolution delay times.
The -c switch used together with the -s switch interrupts the polling after count repetitions.
The -l switch shows detailed low and high memory statistics.
The -a switch shows the available memory (if supported by the running kernel and enabled with sysctl -w vm.meminfo_legacy_layout=0 ; shows zero when unsupported or disabled). The produced output is wider than 80 characters.
The -V switch displays version information.
FILES
/proc/meminfo-- memory information
SEE ALSO
ps(1), slabtop(1), vmstat(8), top(1)
AUTHORS
Written by Brian Edmonds.
Send bug reports to <albert@users.sf.net>
Cohesive Systems
2
free -bt
free -kt
free -mt
free -gt
free -s 1
# statistic
free -l
# version
free -a
free -V
3
This code is to be compiled with gcc memory-user.c -std=gnu99.
#include <stdio.h>
#include <stdlib.h>
#include <sys/time.h>
int main(int argc, char *argv[]) {
if (argc < 2) {
printf("Add argument: number of memory in megabyte\n");
return -1;
}
// the number of megabytes of memory in byte
long size = atoi(argv[1]) * 1024 * 1024;
printf("array size in byte: %ld\n", size);
int timeLength;
if (argc < 3) {
timeLength = -1;
} else {
timeLength = atoi(argv[2]);
}
// allocate memory
int *array = malloc(size);
struct timeval tv;
struct timezone tz;
gettimeofday(&tv, &tz);
long startTime = tv.tv_sec;
while (1) {
if (timeLength != -1) {
gettimeofday(&tv, &tz);
if (tv.tv_sec - startTime >= timeLength) break;
}
for (long i = 0; i < size / sizeof(int); ++i) {
array[i] ^= array[i];
}
}
free(array);
}
4
% free -b;./a.out 100 5 &; free -b -s 1 -c 7
total used free shared buffers cached
Mem: 7648620544 5265272832 2383347712 110592 103882752 335581184
-/+ buffers/cache: 4825808896 2822811648
Swap: 0 0 0
[1] 23439
array size in byte: 104857600
total used free shared buffers cached
Mem: 7648620544 5267058688 2381561856 110592 103882752 335581184
-/+ buffers/cache: 4827594752 2821025792
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5370163200 2278457344 110592 103882752 335581184
-/+ buffers/cache: 4930699264 2717921280
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5370097664 2278522880 110592 103882752 335581184
-/+ buffers/cache: 4930633728 2717986816
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5370224640 2278395904 110592 103882752 335581184
-/+ buffers/cache: 4930760704 2717859840
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5370224640 2278395904 110592 103882752 335581184
-/+ buffers/cache: 4930760704 2717859840
Swap: 0 0 0
[1] + done ./a.out 100 5
total used free shared buffers cached
Mem: 7648620544 5265305600 2383314944 110592 103899136 335581184
-/+ buffers/cache: 4825825280 2822795264
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5265874944 2382745600 110592 103899136 335589376
-/+ buffers/cache: 4826386432 2822234112
Swap: 0 0 0
% free -b;./a.out 100 5 &; PID=$! ; echo PID is $PID ; free -b -s 1 -c 2; kill $PID; free -b -s 1 -c 2
total used free shared buffers cached
Mem: 7648620544 5265784832 2382835712 110592 104521728 335708160
-/+ buffers/cache: 4825554944 2823065600
Swap: 0 0 0
[1] 23606
PID is 23606
array size in byte: 104857600
total used free shared buffers cached
Mem: 7648620544 5266935808 2381684736 110592 104521728 335708160
-/+ buffers/cache: 4826705920 2821914624
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5370548224 2278072320 110592 104521728 335708160
-/+ buffers/cache: 4930318336 2718302208
Swap: 0 0 0
total used free shared buffers cached
Mem: 7648620544 5348904960 2299715584 110592 104521728 335708160
-/+ buffers/cache: 4908675072 2739945472
Swap: 0 0 0
[1] + terminated ./a.out 100 5
total used free shared buffers cached
Mem: 7648620544 5266128896 2382491648 110592 104521728 335708160
-/+ buffers/cache: 4825899008 2822721536
Swap: 0 0 0
5
This is the output of man pmap in AWS EC2. man free result in macOS is different.
PMAP(1) Linux User's Manual PMAP(1)
NAME
pmap - report memory map of a process
SYNOPSIS
pmap [ -x | -d ] [ -q ] pids...
pmap -V
DESCRIPTION
The pmap command reports the memory map of a process or processes.
GENERAL OPTIONS
-x extended Show the extended format.
-d device Show the device format.
-q quiet Do not display some header/footer lines.
-V show version Displays version of program.
EXTENDED AND DEVICE FORMAT FIELDS
Address: start address of map
Kbytes: size of map in kilobytes
RSS: resident set size in kilobytes
Dirty: dirty pages (both shared and private) in kilobytes
Mode: permissions on map: read, write, execute, shared, private (copy on write)
Mapping: file backing the map, or '[ anon ]' for allocated memory, or '[ stack ]' for the program stack
Offset: offset into the file
Device: device name (major:minor)
SEE ALSO
ps(1) pgrep(1)
STANDARDS
No standards apply, but pmap looks an awful lot like a SunOS command.
AUTHOR
Albert Cahalan <albert@users.sf.net> wrote pmap in 2002, and is the current maintainer of the procps collection. Please send bug reports to <procps-feedback@lists.sf.net>.
Linux
8
% ./a.out 100 5 & ; PID=$! ; echo PID is $PID ; sleep 1; pmap $PID; kill $PID;
[1] 23866
PID is 23866
array size in byte: 104857600
23866: ./a.out 100 5
0000000000400000 4K r-x-- /mnt/data/develop/kenjiotsuka/a.out
0000000000600000 4K rw--- /mnt/data/develop/kenjiotsuka/a.out
00007fa4e146b000 102404K rw--- [ anon ]
00007fa4e786c000 1804K r-x-- /lib64/libc-2.17.so
00007fa4e7a2f000 2048K ----- /lib64/libc-2.17.so
00007fa4e7c2f000 16K r---- /lib64/libc-2.17.so
00007fa4e7c33000 8K rw--- /lib64/libc-2.17.so
00007fa4e7c35000 20K rw--- [ anon ]
00007fa4e7c3a000 136K r-x-- /lib64/ld-2.17.so
00007fa4e7e4e000 12K rw--- [ anon ]
00007fa4e7e59000 8K rw--- [ anon ]
00007fa4e7e5b000 4K r---- /lib64/ld-2.17.so
00007fa4e7e5c000 4K rw--- /lib64/ld-2.17.so
00007fa4e7e5d000 4K rw--- [ anon ]
00007ffda7971000 132K rw--- [ stack ]
00007ffda79db000 12K r---- [ anon ]
00007ffda79de000 8K r-x-- [ anon ]
ffffffffff600000 4K r-x-- [ anon ]
total 106632K
% ./a.out 100 5 & ; PID=$! ; echo PID is $PID ; sleep 1; pmap -x $PID; kill $PID;
[1] 23875
PID is 23875
array size in byte: 104857600
23875: ./a.out 100 5
Address Kbytes RSS Dirty Mode Mapping
0000000000400000 4 4 0 r-x-- a.out
0000000000400000 4 0 0 r-x-- a.out
0000000000600000 4 4 4 rw--- a.out
0000000000600000 4 0 0 rw--- a.out
00007f94aefcd000 102404 102404 102404 rw--- [ anon ]
00007f94aefcd000 102404 0 0 rw--- [ anon ]
00007f94b53ce000 1804 1076 0 r-x-- libc-2.17.so
00007f94b53ce000 1804 0 0 r-x-- libc-2.17.so
00007f94b5591000 2048 0 0 ----- libc-2.17.so
00007f94b5591000 2048 0 0 ----- libc-2.17.so
00007f94b5791000 16 16 16 r---- libc-2.17.so
00007f94b5791000 16 0 0 r---- libc-2.17.so
00007f94b5795000 8 8 8 rw--- libc-2.17.so
00007f94b5795000 8 0 0 rw--- libc-2.17.so
00007f94b5797000 20 12 12 rw--- [ anon ]
00007f94b5797000 20 0 0 rw--- [ anon ]
00007f94b579c000 136 132 0 r-x-- ld-2.17.so
00007f94b579c000 136 0 0 r-x-- ld-2.17.so
00007f94b59b0000 12 12 12 rw--- [ anon ]
00007f94b59b0000 12 0 0 rw--- [ anon ]
00007f94b59bb000 8 8 8 rw--- [ anon ]
00007f94b59bb000 8 0 0 rw--- [ anon ]
00007f94b59bd000 4 4 4 r---- ld-2.17.so
00007f94b59bd000 4 0 0 r---- ld-2.17.so
00007f94b59be000 4 4 4 rw--- ld-2.17.so
00007f94b59be000 4 0 0 rw--- ld-2.17.so
00007f94b59bf000 4 4 4 rw--- [ anon ]
00007f94b59bf000 4 0 0 rw--- [ anon ]
00007ffd6ce34000 132 16 16 rw--- [ stack ]
00007ffd6ce34000 132 0 0 rw--- [ stack ]
00007ffd6ce56000 12 0 0 r---- [ anon ]
00007ffd6ce56000 12 0 0 r---- [ anon ]
00007ffd6ce59000 8 4 0 r-x-- [ anon ]
00007ffd6ce59000 8 0 0 r-x-- [ anon ]
ffffffffff600000 4 0 0 r-x-- [ anon ]
ffffffffff600000 4 0 0 r-x-- [ anon ]
---------------- ------ ------ ------
total kB 106632 103708 102492