0 directory

01. Overview of commands

The pmap command is used to report the memory mapping relationship of the process. It is a good tool for Linux debugging and operation.

02. Command format

 pmap [option] process number [...]

03. Common Options

- x: Display extended format
 - d: Display device format
 - q: No head and tail lines are displayed
 - V: Display the specified version

04. Reference examples

Extended Format and Device Format Domain

Address: start address of map image start address
 Kbytes: size of map in kilobytes image size
 RSS: resident set size in kilobytes resident set size
 Dirty: dirty pages (both shared and private) in kilobytes dirty page size
 Mode: permissions on map image permissions: r=read, w=write, x=execute, s=shared, p=private (copy on write)  
Mapping: file backing the map, or'[anon]'for allocated memory, or'[stack]' for the program stack. Image support file, [anon] for allocated memory [stack] for program stack
 Offset: offset into the file file offset
 Device: device name (major: minor) device name

4.1 View the device format of process 1

[root@localhost ~]# pmap  -d 1
1:   /usr/lib/systemd/systemd --switched-root --system --deserialize 22
Address           Kbytes Mode  Offset           Device    Mapping
0000558b9e31a000    1408 r-x-- 0000000000000000 008:00003 systemd
0000558b9e679000     140 r---- 000000000015f000 008:00003 systemd
0000558b9e69c000       4 rw--- 0000000000182000 008:00003 systemd
0000558b9f184000    1292 rw--- 0000000000000000 000:00000   [ anon ]
00007effac000000     164 rw--- 0000000000000000 000:00000   [ anon ]
00007effac029000   65372 ----- 0000000000000000 000:00000   [ anon ]
00007effb4000000     164 rw--- 0000000000000000 000:00000   [ anon ]
00007effb4029000   65372 ----- 0000000000000000 000:00000   [ anon ]

4.2 View the device format of process 1 without showing the head and tail lines

[root@localhost ~]# pmap  -d -q 1
1:   /usr/lib/systemd/systemd --switched-root --system --deserialize 22
0000558b9e31a000    1408 r-x-- 0000000000000000 008:00003 systemd
0000558b9e679000     140 r---- 000000000015f000 008:00003 systemd
0000558b9e69c000       4 rw--- 0000000000182000 008:00003 systemd
0000558b9f184000    1292 rw--- 0000000000000000 000:00000   [ anon ]
00007effac000000     164 rw--- 0000000000000000 000:00000   [ anon ]
00007effac029000   65372 ----- 0000000000000000 000:00000   [ anon ]
00007effb4000000     164 rw--- 0000000000000000 000:00000   [ anon ]

4.3 View the Extended Format of Process 1

[root@localhost ~]# pmap  -x 1 
1:   /usr/lib/systemd/systemd --switched-root --system --deserialize 22
Address           Kbytes     RSS   Dirty Mode  Mapping
0000558b9e31a000    1408     952       0 r-x-- systemd
0000558b9e679000     140     132     132 r---- systemd
0000558b9e69c000       4       4       4 rw--- systemd
0000558b9f184000    1292    1100    1100 rw---   [ anon ]
00007effac000000     164      12      12 rw---   [ anon ]
00007effac029000   65372       0       0 -----   [ anon ]

4.4 Loop shows the last line of device format for process 666, one second apart

[root@localhost ~]# while true; do pmap -d 666 |tail -1;sleep 1;done
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K
mapped: 115304K    writeable/private: 416K    shared: 28K

5 appendix

Reference resources: [Linux] A step-by-step summary of the series of Linux tutorials