Detailed explanation of pmap command for Linux performance testing

The pmap command is used to display the memory status of one or more processes. This article will share with you the detailed explanation of the Linux performance test pmap command. Friends who need it can refer to it

Name:

 pmap - report memory map of a process(查看进程的内存映像信息)

Usage

 pmap [ -x | -d ] [ -q ] pids...
    pmap -V

Option meaning

 -x  extended    Show the extended format. 显示扩展格式
    -d  device     Show the device format.  显示设备格式
    -q  quiet     Do not display some header/footer lines. 不显示头尾行
    -V  show version  Displays version of program. 显示版本

Extended format and device format fields:

Address: start address of map 映像起始地址
    Kbytes: size of map in kilobytes 映像大小
    RSS: resident set size in kilobytes 驻留集大小
    Dirty: dirty pages (both shared and private) in kilobytes 脏页大小
    Mode: permissions on map 映像权限: 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. 映像支持文件,[anon]为已分配内存 [stack]为程序堆栈
    Offset: offset into the file 文件偏移
    Device: device name (major:minor) 设备名

Example:

View the device format of process 1

[root@C44 ~]# pmap -d 1
1:  init [5]          
Address  Kbytes Mode Offset      Device  Mapping
00934000   88 r-x-- 0000000000000000 008:00005 ld-2.3.4.so
0094a000    4 r---- 0000000000015000 008:00005 ld-2.3.4.so
0094b000    4 rw--- 0000000000016000 008:00005 ld-2.3.4.so
0094e000  1188 r-x-- 0000000000000000 008:00005 libc-2.3.4.so
00a77000    8 r---- 0000000000129000 008:00005 libc-2.3.4.so
00a79000    8 rw--- 000000000012b000 008:00005 libc-2.3.4.so
00a7b000    8 rw--- 0000000000a7b000 000:00000  [ anon ]
00a85000   52 r-x-- 0000000000000000 008:00005 libsepol.so.1
00a92000    4 rw--- 000000000000c000 008:00005 libsepol.so.1
00a93000   32 rw--- 0000000000a93000 000:00000  [ anon ]
00d9d000   52 r-x-- 0000000000000000 008:00005 libselinux.so.1
00daa000    4 rw--- 000000000000d000 008:00005 libselinux.so.1
08048000   28 r-x-- 0000000000000000 008:00005 init
0804f000    4 rw--- 0000000000007000 008:00005 init
084e1000   132 rw--- 00000000084e1000 000:00000  [ anon ]
b7f5d000    8 rw--- 00000000b7f5d000 000:00000  [ anon ]
bffee000   72 rw--- 00000000bffee000 000:00000  [ stack ]
ffffe000    4 ----- 0000000000000000 000:00000  [ anon ]
mapped: 1700K  writeable/private: 276K  shared: 0K
[root@C44 ~]#

The value of the last line

mapped indicates the size of the virtual address space mapped by the process, which is pre-allocated by the process The size of virtual memory, that is, the vsz

writeable/private output from ps indicates the size of the private address space occupied by the process, which is the size of the memory actually used by the process.

shared indicates that the process is shared with other processes. The memory size

View the device format of process 1, do not display the first and last lines

[root@C44 ~]# pmap -d -q 1
1:  init [5]          
00934000   88 r-x-- 0000000000000000 008:00005 ld-2.3.4.so
0094a000    4 r---- 0000000000015000 008:00005 ld-2.3.4.so
0094b000    4 rw--- 0000000000016000 008:00005 ld-2.3.4.so
0094e000  1188 r-x-- 0000000000000000 008:00005 libc-2.3.4.so
00a77000    8 r---- 0000000000129000 008:00005 libc-2.3.4.so
00a79000    8 rw--- 000000000012b000 008:00005 libc-2.3.4.so
00a7b000    8 rw--- 0000000000a7b000 000:00000  [ anon ]
00a85000   52 r-x-- 0000000000000000 008:00005 libsepol.so.1
00a92000    4 rw--- 000000000000c000 008:00005 libsepol.so.1
00a93000   32 rw--- 0000000000a93000 000:00000  [ anon ]
00d9d000   52 r-x-- 0000000000000000 008:00005 libselinux.so.1
00daa000    4 rw--- 000000000000d000 008:00005 libselinux.so.1
08048000   28 r-x-- 0000000000000000 008:00005 init
0804f000    4 rw--- 0000000000007000 008:00005 init
084e1000   132 rw--- 00000000084e1000 000:00000  [ anon ]
b7f5d000    8 rw--- 00000000b7f5d000 000:00000  [ anon ]
bffee000   72 rw--- 00000000bffee000 000:00000  [ stack ]
ffffe000    4 ----- 0000000000000000 000:00000  [ anon ]
[root@C44 ~]#

View the extended format of process 1

[root@C44 ~]# pmap -x 1
1:  init [5]          
Address  Kbytes   RSS  Anon Locked Mode  Mapping
00934000   88    -    -    - r-x-- ld-2.3.4.so
0094a000    4    -    -    - r---- ld-2.3.4.so
0094b000    4    -    -    - rw--- ld-2.3.4.so
0094e000  1188    -    -    - r-x-- libc-2.3.4.so
00a77000    8    -    -    - r---- libc-2.3.4.so
00a79000    8    -    -    - rw--- libc-2.3.4.so
00a7b000    8    -    -    - rw---  [ anon ]
00a85000   52    -    -    - r-x-- libsepol.so.1
00a92000    4    -    -    - rw--- libsepol.so.1
00a93000   32    -    -    - rw---  [ anon ]
00d9d000   52    -    -    - r-x-- libselinux.so.1
00daa000    4    -    -    - rw--- libselinux.so.1
08048000   28    -    -    - r-x-- init
0804f000    4    -    -    - rw--- init
084e1000   132    -    -    - rw---  [ anon ]
b7f5d000    8    -    -    - rw---  [ anon ]
bffee000   72    -    -    - rw---  [ stack ]
ffffe000    4    -    -    - -----  [ anon ]
-------- ------- ------- ------- -------
total kB  1700    -    -    -
[root@C44 ~]#

Display the last line of the device format of process 3066 in a loop, with an interval of 2 seconds,

[root@C44 ~]# while true; do pmap -d 3066 | tail -1; sleep 2; done
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K
mapped: 5412K  writeable/private: 2028K  shared: 0K

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