What is pmap linux
The pmap utility prints information about the address space of a process.
OPTIONS
The following options are supported:
Prints anonymous and swap reservations for shared mappings.
Force. Grabs the target process even if another process has control.
Prints the process’s reserved addresses.
Prints HAT page size information.
USAGE
The pmap utility prints information about the address space of a process.
/usr/bin/pmap [ -rslF ] [ pid | core ] .
By default, pmap displays the mappings in the virtual address order they are mapped into the process. The mapping size, flags and mapped object name are shown.
/usr/bin/pmap -x [ -aslF ] [ pid | core ] .
The -x option displays additional information per mapping. The size of each mapping, the amount of resident physical memory, the amount of anonymous memory, and the amount of memory locked is shown with this option.
/usr/bin/pmap -S [ -alF ] [ pid | core ] .
The -S option displays swap reservation information per mapping.
DISPLAY FORMATS
One line of output is printed for each mapping within the process, unless the -s option is specified, where one line is printed for a contiguous mapping of each hardware translation page size.
The first column of output represents the starting virtual address of each mapping. Virtual addresses are displayed in ascending order.
The virtual size of each mapping.
The amount of physical memory resident for each mapping, including that which is shared with other address spaces.
The amount of anonymous memory is reported for each mapping. Anonymous memory shared with other address spaces is not included, unless the -a option is specified.
Anonymous memory is reported for the process heap, stack, for ‘copy on write’ pages with mappings mapped with MAP_PRIVATE.
The number of pages locked within the mapping. Typical examples are memory locked with mlock() and System V shared memory created with SHM_SHARE_MMU.
The virtual memory permissions are shown for each mapping. Valid permissions are:
The mapping may be read by the process.
The mapping may be written by the process.
Instructions that reside within the mapping may be executed by the process.
Flags showing additional information for each mapping may be displayed:
The mapping is shared such that changes made in the observed address space are committed to the mapped file, and are visible from all other processes sharing the mapping.
Swap space is not reserved for this mapping. Mappings created with MAP_NORESERVE and System V ISM shared memory mappings do not reserve swap space.
A descriptive name for each mapping. The following major types of names are displayed for mappings:
- A mapped file: For mappings between a process and a file, the pmap command attempts to resolve the file name for each mapping. If the file name cannot be resolved, pmap displays the major and minor number of the device containing the file, and the file system inode number of the file.
- Anonymous memory: Memory not relating to any named object or file within the file system is reported as [ anon ]. The pmap command displays common names for certain known anonymous memory mappings, such as: [ heap ] The process heap. [ stack ] The process stack. If the common name for the mapping is unknown, pmap displays [ anon ] as the mapping name.
- System V Shared Memory: Mappings created using System V shared memory system calls are reported with the names shown below: shmid=n: The mapping is a System V shared memory mapping. The shared memory identifier that the mapping was created with is reported. ism shmid=n: The mapping is an «Intimate Shared Memory» variant of System V shared memory. ISM mappings are created with the SHM_SHARE_MMU flag set, in accordance with shmat(2) (see shmop(2)). dism shmid=n: The mapping is a pageable variant of ISM. Pageable ISM is created with the SHM_PAGEABLE flag set in accordance with shmat(2) (see shmop(2)).
- Other: Mappings of other objects, including devices such as frame buffers. No mapping name is shown for other mapped objects.
EXAMPLES
Example 1 Displaying process mappings
By default, pmap prints one line for each mapping within the address space of the target process. The following example displays the address space of a typical bourne shell:
example$ pmap 102905 102905: sh 00010000 192K r-x-- /usr/bin/ksh 00040000 8K rwx-- /usr/bin/ksh 00042000 40K rwx-- [ heap ] FF180000 664K r-x-- /usr/lib/libc.so.1 FF236000 24K rwx-- /usr/lib/libc.so.1 FF23C000 8K rwx-- /usr/lib/libc.so.1 FF250000 8K rwx-- [ anon ] FF260000 16K r-x-- /usr/lib/en_US.ISO8859-1.so.2 FF272000 16K rwx-- /usr/lib/en_US.ISO8859-1.so.2 FF280000 560K r-x-- /usr/lib/libnsl.so.1 FF31C000 32K rwx-- /usr/lib/libnsl.so.1 FF324000 32K rwx-- /usr/lib/libnsl.so.1 FF340000 16K r-x-- /usr/lib/libc_psr.so.1 FF350000 16K r-x-- /usr/lib/libmp.so.2 FF364000 8K rwx-- /usr/lib/libmp.so.2 FF380000 40K r-x-- /usr/lib/libsocket.so.1 FF39A000 8K rwx-- /usr/lib/libsocket.so.1 FF3A0000 8K r-x-- /usr/lib/libdl.so.1 FF3B0000 8K rwx-- [ anon ] FF3C0000 152K r-x-- /usr/lib/ld.so.1 FF3F6000 8K rwx-- /usr/lib/ld.so.1 FFBFC000 16K rw--- [ stack ] total 1880K
Example 2 Displaying memory allocation and mapping types
The -x option can be used to provide information about the memory allocation and mapping types per mapping. The amount of resident, non-shared anonymous, and locked memory is shown for each mapping:
example$ pmap -x 102908 102908: sh Address Kbytes Resident Anon Locked Mode Mapped File 00010000 88 88 - - r-x-- sh 00036000 8 8 8 - rwx-- sh 00038000 16 16 16 - rwx-- [ heap ] FF260000 16 16 - - r-x-- en_US.ISO8859-1.so.2 FF272000 16 16 - - rwx-- en_US.ISO8859-1.so.2 FF280000 664 624 - - r-x-- libc.so.1 FF336000 32 32 8 - rwx-- libc.so.1 FF360000 16 16 - - r-x-- libc_psr.so.1 FF380000 24 24 - - r-x-- libgen.so.1 FF396000 8 8 - - rwx-- libgen.so.1 FF3A0000 8 8 - - r-x-- libdl.so.1 FF3B0000 8 8 8 - rwx-- [ anon ] FF3C0000 152 152 - - r-x-- ld.so.1 FF3F6000 8 8 8 - rwx-- ld.so.1 FFBFE000 8 8 8 - rw--- [ stack ] -------- ----- ----- ----- ------ total Kb 1072 1032 56 -
The amount of incremental memory used by each additional instance of a process can be estimated by using the resident and anonymous memory counts of each mapping.
In the above example, the bourne shell has a resident memory size of 1032Kbytes. However, a large amount of the physical memory used by the shell is shared with other instances of shell. Another identical instance of the shell will share physical memory with the other shell where possible, and allocate anonymous memory for any non-shared portion. In the above example, each additional bourne shell uses approximately 56Kbytes of additional physical memory.
A more complex example shows the output format for a process containing different mapping types. In this example, the mappings are as follows:
0001000: Executable text, mapped from 'maps' program 0002000: Executable data, mapped from 'maps' program 0002200: Program heap 0300000: A mapped file, mapped MAP_SHARED 0400000: A mapped file, mapped MAP_PRIVATE 0500000: A mapped file, mapped MAP_PRIVATE | MAP_NORESERVE 0600000: Anonymous memory, created by mapping /dev/zero 0700000: Anonymous memory, created by mapping /dev/zero with MAP_NORESERVE 0800000: A DISM shared memory mapping, created with SHM_PAGEABLE with 8MB locked via mlock(2) 0900000: A DISM shared memory mapping, created with SHM_PAGEABLE, with 4MB of its pages touched. 0A00000: A DISM shared memory mapping, created with SHM_PAGEABLE, with none of its pages touched. 0B00000: An ISM shared memory mapping, created with SHM_SHARE_MMU
example$ pmap -xs 15492 15492: ./maps Address Kbytes RSS Anon Locked Mode Mapped File 00010000 8 8 - - r-x-- maps 00020000 8 8 8 - rwx-- maps 00022000 20344 16248 16248 - rwx-- [ heap ] 03000000 1024 1024 - - rw-s- dev:0,2 ino:4628487 04000000 1024 1024 512 - rw--- dev:0,2 ino:4628487 05000000 1024 1024 512 - rw--R dev:0,2 ino:4628487 06000000 1024 1024 1024 - rw--- [ anon ] 07000000 512 512 512 - rw--R [ anon ] 08000000 8192 8192 - 8192 rwxs- [ dism shmid=0x5] 09000000 8192 4096 - - rwxs- [ dism shmid=0x4] 0A000000 8192 8192 - 8192 rwxsR [ ism shmid=0x2 ] 0B000000 8192 8192 - 8192 rwxsR [ ism shmid=0x3 ] FF280000 680 672 - - r-x-- libc.so.1 FF33A000 32 32 32 - rwx-- libc.so.1 FF390000 8 8 - - r-x-- libc_psr.so.1 FF3A0000 8 8 - - r-x-- libdl.so.1 FF3B0000 8 8 8 - rwx-- [ anon ] FF3C0000 152 152 - - r-x-- ld.so.1 FF3F6000 8 8 8 - rwx-- ld.so.1 FFBFA000 24 24 24 - rwx-- [ stack ] -------- ------- ------- ------- ------- total Kb 50464 42264 18888 16384
Example 3 Displaying Page Size Information
The -s option can be used to display the hardware translation page sizes for each portion of the address space. (See memcntl(2) for futher information on Solaris multiple page size support).
In the example below, we can see that the majority of the mappings are using an 8K-Byte page size, while the heap is using a 4M-Byte page size.
Notice that non-contiguous regions of resident pages of the same page size are reported as separate mappings. In the example below, the libc.so library is reported as separate mappings, since only some of the libc.so text is resident:
example$ pmap -xs 15492 15492: ./maps Address Kbytes RSS Anon Locked Pgsz Mode Mapped File 00010000 8 8 - - 8K r-x-- maps 00020000 8 8 8 - 8K rwx-- maps 00022000 3960 3960 3960 - 8K rwx-- [ heap ] 00400000 8192 8192 8192 - 4M rwx-- [ heap ] 00C00000 4096 - - - - rwx-- [ heap ] 01000000 4096 4096 4096 - 4M rwx-- [ heap ] 03000000 1024 1024 - - 8K rw-s- dev:0,2 ino:4628487 04000000 512 512 512 - 8K rw--- dev:0,2 ino:4628487 04080000 512 512 - - - rw--- dev:0,2 ino:4628487 05000000 512 512 512 - 8K rw--R dev:0,2 ino:4628487 05080000 512 512 - - - rw--R dev:0,2 ino:4628487 06000000 1024 1024 1024 - 8K rw--- [ anon ] 07000000 512 512 512 - 8K rw--R [ anon ] 08000000 8192 8192 - 8192 - rwxs- [ dism shmid=0x5 ] 09000000 4096 4096 - - 8K rwxs- [ dism shmid=0x4 ] 0A000000 4096 - - - - rwxs- [ dism shmid=0x2 ] 0B000000 8192 8192 - 8192 4M rwxsR [ ism shmid=0x3 ] FF280000 136 136 - - 8K r-x-- libc.so.1 FF2A2000 120 120 - - - r-x-- libc.so.1 FF2C0000 128 128 - - 8K r-x-- libc.so.1 FF2E0000 200 200 - - - r-x-- libc.so.1 FF312000 48 48 - - 8K r-x-- libc.so.1 FF31E000 48 40 - - - r-x-- libc.so.1 FF33A000 32 32 32 - 8K rwx-- libc.so.1 FF390000 8 8 - - 8K r-x-- libc_psr.so.1 FF3A0000 8 8 - - 8K r-x-- libdl.so.1 FF3B0000 8 8 8 - 8K rwx-- [ anon ] FF3C0000 152 152 - - 8K r-x-- ld.so.1 FF3F6000 8 8 8 - 8K rwx-- ld.so.1 FFBFA000 24 24 24 - 8K rwx-- [ stack ] -------- ------- ------- ------- ------- total Kb 50464 42264 18888 16384
Example 4 Displaying swap reservations
The -S option can be used to describe the swap reservations for a process. The amount of swap space reserved is displayed for each mapping within the process. Swap reservations are reported as zero for shared mappings, since they are accounted for only once system wide.
example$ pmap -S 15492 15492: ./maps Address Kbytes Swap Mode Mapped File 00010000 8 - r-x-- maps 00020000 8 8 rwx-- maps 00022000 20344 20344 rwx-- [ heap ] 03000000 1024 - rw-s- dev:0,2 ino:4628487 04000000 1024 1024 rw--- dev:0,2 ino:4628487 05000000 1024 512 rw--R dev:0,2 ino:4628487 06000000 1024 1024 rw--- [ anon ] 07000000 512 512 rw--R [ anon ] 08000000 8192 - rwxs- [ dism shmid=0x5] 09000000 8192 - rwxs- [ dism shmid=0x4] 0A000000 8192 - rwxs- [ dism shmid=0x2] 0B000000 8192 - rwxsR [ ism shmid=0x3] FF280000 680 - r-x-- libc.so.1 FF33A000 32 32 rwx-- libc.so.1 FF390000 8 - r-x-- libc_psr.so.1 FF3A0000 8 - r-x-- libdl.so.1 FF3B0000 8 8 rwx-- [ anon ] FF3C0000 152 - r-x-- ld.so.1 FF3F6000 8 8 rwx-- ld.so.1 FFBFA000 24 24 rwx-- [ stack ] -------- ------- ------- total Kb 50464 23496
The swap reservation information can be used to estimate the amount of virtual swap used by each additional process. Each process consumes virtual swap from a global virtual swap pool. Global swap reservations are reported by the ‘avail‘ field of the swap(1M) command.
EXIT STATUS
The following exit values are returned: