Understanding F5 BIG-IP Memory Usage
Any non-tmsh command you use in the HMS bash shell (like free) will generally only relate to the HMS. This is why there is an apparent discrepancy between the tmsh “show system memory” command and the Linux “free” command:
[root@F5-BIG-IP:Active:Changes Pending] config # tmsh show sys memory | head
Sys::System Memory Information
——————————————————————
Memory Used(bytes) Current Average Max(since 03/30/15 10:17:01)
——————————————————————
Total Phys Memory 7.8G 7.8G 7.8G
OS Used Memory 7.6G 7.6G 7.6G
TMM Alloc Memory 2.8G 2.8G 2.8G
TMM Used Memory 650.1M 649.8M 650.1M
OS Used Swap 0 0 0
The TMM shows low usage but the Linux OS shows only 160MB free out of 7.8GB:
[root@F5-BIG-IP:Active:Changes Pending] config # free -m
total used free shared buffers cached
Mem: 7996 7836 160 0 565 1373
-/+ buffers/cache: 5897 2098
Swap: 1023 0 1023
[root@F5-BIG-IP:Active:Changes Pending] config #
Top is one exception and will actually give you valid figures for CPU and memory (for the TMM processes), this is the only non-tmsh command you should rely upon. To avoid confusion it’s best to simply rely on tmsh commands:
top – 13:21:24 up 484 days, 2:38, 1 user, load average: 0.00, 0.03, 0.00
Tasks: 295 total, 1 running, 294 sleeping, 0 stopped, 0 zombie
Cpu(s): 9.3%us, 3.0%sy, 0.7%ni, 87.1%id, 0.0%wa, 0.0%hi, 0.0%si, 0.0%st
Mem: 8188268k total, 8025028k used, 163240k free, 578620k buffers
Swap: 1048568k total, 0k used, 1048568k free, 1406236k cachedPID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
30872 root RT 0 958m 64m 33m S 10.6 0.8 66033:18 tmm
30874 root RT 0 1019m 125m 94m S 10.2 1.6 65595:50 tmm
30871 root RT 0 958m 64m 33m S 9.9 0.8 66134:06 tmm
30873 root RT 0 1019m 125m 94m S 9.9 1.6 71945:39 tmm
7017 root 25 5 14752 5640 2240 S 3.3 0.1 22308:35 merged
6133 root 20 0 26008 15m 2856 S 1.7 0.2 3341:04 statsd
7023 root 20 0 27748 14m 7060 S 1.7 0.2 11418:43 pfmand
1241 root 20 0 2528 1224 832 R 0.7 0.0 0:00.07 top
6670 root 20 0 113m 65m 11m S 0.7 0.8 4711:47 mcpd
5328 root 20 0 3204 976 824 S 0.3 0.0 1725:57 lopd
6024 root 20 0 1932 808 680 S 0.3 0.0 2175:09 LCDd
6388 root 20 0 26656 25m 17m S 0.3 0.3 381:20.44 sod
6407 root 20 0 5784 2368 1148 S 0.3 0.0 3879:41 ntlmconnpool
7039 root 20 0 172m 52m 4788 S 0.3 0.7 413:50.77 java
28625 root 20 0 99.7m 18m 8948 S 0.3 0.2 2040:50 apmd
1 root 20 0 2160 660 564 S 0.0 0.0 0:46.12 init
2 root 20 0 0 0 0 S 0.0 0.0 0:03.85 kthreadd
3 root RT 0 0 0 0 S 0.0 0.0 0:02.32 migration/0
4 root 20 0 0 0 0 S 0.0 0.0 0:00.03 ksoftirqd/0
5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0
6 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/0
7 root RT 0 0 0 0 S 0.0 0.0 0:10.20 migration/1
8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/1
9 root 20 0 0 0 0 S 0.0 0.0 0:00.08 ksoftirqd/1
10 root RT 0 0 0 0 S 0.0 0.0 0:00.08 watchdog/1
11 root RT 0 0 0 0 S 0.0 0.0 0:04.01 migration/2
12 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/2
13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/2
14 root RT 0 0 0 0 S 0.0 0.0 0:00.00 watchdog/2
15 root RT 0 0 0 0 S 0.0 0.0 1:26.87 migration/3
16 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/3