| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Date: Tue, 01 May 2007 21:31:27 +0200
From: Christian Schmidt <lkml@...add.de>
To: linux-kernel@...r.kernel.org
Subject: Memory consumption on linux
Hi all,
I could not find good documentation anywhere on the memory usage of
linux, or rather, how to interpret the output of the various tools
dealing with memory consumption.
First of, generally - there's resident, virtual and shared memory for
each process, and global buffers/cache.
Global cache is easy to understand - file system / inode caches. What
exactly is buffers, though?
How do virtual, resident and shared memory relate to each other, though?
>From my observation I assume:
- Virtual: All of the memory the program has allocated, including
overcommitted heap
- Resident: The actually used memory, including mmap()ed files whether
they are locked into memory or not (?)
- Shared: Dynamic libraries that are shared among multiple programs,
shared memory, and mmap()ed files
How are mmap()ed files handled in the global scheme of the kernel memory
management anyway? It seems they are not deducted from the globally
available memory unless explicitly locked with MAP_LOCKED?
And, how does process memory relate to system memory? Usually the sum of
the resident memory (ps -o rss) is way off from the used memory
displayed by free. I'm posting data from two machines down below, where
you can see discrepancies in either direction, in one case 2G more free
than resident, in the other case 60M less.
Is there a way to get more detailed information on process and kernel
memory usage? I assume that dm-crypto and software-raid use memory that
does not show up anywhere.
Best regards,
Christian
one machine (sum > free):
free:
total used free shared buffers cached
Mem: 4109304 4045820 63484 0 350264 3048268
-/+ buffers/cache: 647288 3462016
swap: 1953120 2724 1950396
ps -aeo rss | awk '{sum+=$1} END {print sum}'
2611756
top (sorted by memory usage, top 4 processes)
Mem: 4109304k total, 4045196k used, 64108k free, 350268k buffers
Swap: 1953120k total, 2724k used, 1950396k free, 3048268k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
29587 micki 15 0 2033m 1.1g 957m S 135 27.3 28566:57 dynamips
27672 micki 15 0 1981m 1.1g 957m S 158 26.8 31142:47 dynamips
29244 vmware 5 -10 381m 288m 277m S 1 7.2 1169:27 vmware-vmx
24278 root 15 0 19056 14m 4244 S 0 0.4 9:15.99 vmware-serv
dynamips and vmware both mmap() the ram of the emulated machines
(dynamips emulates cisco routers). Still, obviously the majority of the
resident memory is "free", or rather "cached".
another machine (sum < free):
free:
total used free shared buffers cached
Mem: 1024752 978896 45856 0 16768 250908
-/+ buffers/cache: 711220 313532
Swap: 0 0 0
[~]>ps -aeo rss | awk '{sum+=$1} END {print sum}'
658032
top (sorted by memory usage, top 8 processes):
Mem: 1024752k total, 978612k used, 46140k free, 16576k buffers
Swap: 0k total, 0k used, 0k free, 250876k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
7217 root 16 0 479m 472m 728 S 0.0 47.2 0:04.17 rpc.mountd
1699 bofh 15 0 52140 30m 1792 S 0.0 3.0 0:27.46 imapd
5663 mysql 16 0 146m 29m 5052 S 0.0 3.0 0:05.41 mysqld
5804 root 16 0 117m 18m 6788 S 0.0 1.8 0:01.30 apache2
12535 apache 18 0 334m 13m 1864 S 0.0 1.4 0:00.00 apache2
12533 apache 18 0 334m 13m 1860 S 0.0 1.4 0:00.00 apache2
12511 apache 18 0 117m 12m 856 S 0.0 1.2 0:00.00 apache2
18861 named 25 0 47592 5976 2128 S 0.0 0.6 0:42.23 named
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists