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NAME | DESCRIPTION | SEE ALSO | COLOPHON |
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proc_pid_smaps(5) File Formats Manual proc_pid_smaps(5)
/proc/pid/smaps - XXX: What does 's' in "smaps" stand for?
/proc/pid/smaps (since Linux 2.6.14)
This file shows memory consumption for each of the
process's mappings. (The pmap(1) command displays similar
information, in a form that may be easier for parsing.)
For each mapping there is a series of lines such as the
following:
00400000-0048a000 r-xp 00000000 fd:03 960637 /bin/bash
Size: 552 kB
Rss: 460 kB
Pss: 100 kB
Shared_Clean: 452 kB
Shared_Dirty: 0 kB
Private_Clean: 8 kB
Private_Dirty: 0 kB
Referenced: 460 kB
Anonymous: 0 kB
AnonHugePages: 0 kB
ShmemHugePages: 0 kB
ShmemPmdMapped: 0 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 0 kB
ProtectionKey: 0
VmFlags: rd ex mr mw me dw
The first of these lines shows the same information as is
displayed for the mapping in /proc/pid/maps. The
following lines show the size of the mapping, the amount
of the mapping that is currently resident in RAM ("Rss"),
the process's proportional share of this mapping ("Pss"),
the number of clean and dirty shared pages in the mapping,
and the number of clean and dirty private pages in the
mapping. "Referenced" indicates the amount of memory
currently marked as referenced or accessed. "Anonymous"
shows the amount of memory that does not belong to any
file. "Swap" shows how much would-be-anonymous memory is
also used, but out on swap.
The "KernelPageSize" line (available since Linux 2.6.29)
is the page size used by the kernel to back the virtual
memory area. This matches the size used by the MMU in the
majority of cases. However, one counter-example occurs on
PPC64 kernels whereby a kernel using 64 kB as a base page
size may still use 4 kB pages for the MMU on older
processors. To distinguish the two attributes, the
"MMUPageSize" line (also available since Linux 2.6.29)
reports the page size used by the MMU.
The "Locked" indicates whether the mapping is locked in
memory or not.
The "ProtectionKey" line (available since Linux 4.9, on
x86 only) contains the memory protection key (see
pkeys(7)) associated with the virtual memory area. This
entry is present only if the kernel was built with the
CONFIG_X86_INTEL_MEMORY_PROTECTION_KEYS configuration
option (since Linux 4.6).
The "VmFlags" line (available since Linux 3.8) represents
the kernel flags associated with the virtual memory area,
encoded using the following two-letter codes:
rd - readable
wr - writable
ex - executable
sh - shared
mr - may read
mw - may write
me - may execute
ms - may share
gd - stack segment grows down
pf - pure PFN range
dw - disabled write to the mapped file
lo - pages are locked in memory
io - memory mapped I/O area
sr - sequential read advise provided
rr - random read advise provided
dc - do not copy area on fork
de - do not expand area on remapping
ac - area is accountable
nr - swap space is not reserved for the area
ht - area uses huge tlb pages
sf - perform synchronous page faults (since Linux 4.15)
nl - non-linear mapping (removed in Linux 4.0)
ar - architecture specific flag
wf - wipe on fork (since Linux 4.14)
dd - do not include area into core dump
sd - soft-dirty flag (since Linux 3.13)
mm - mixed map area
hg - huge page advise flag
nh - no-huge page advise flag
mg - mergeable advise flag
um - userfaultfd missing pages tracking (since Linux 4.3)
uw - userfaultfd wprotect pages tracking (since Linux 4.3)
The /proc/pid/smaps file is present only if the
CONFIG_PROC_PAGE_MONITOR kernel configuration option is
enabled.
proc(5)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 proc_pid_smaps(5)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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