Question

Memory Usage

  • Posted May 2, 2013

Please anyone can help me to understand this? I want to find out why so many memory is used, how to optimize memory usage. is it the RES shows the memory usage? Also why I got multiple getty and postgres processes? that doesn’t seems normal…

Any help is appreciated. Thanks

KiB Mem: 1019328 total, 950260 used, 69068 free, 21820 buffers KiB Swap: 524284 total, 0 used, 524284 free, 569288 cached PID to renice ^[^[^[^C PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
818 root 20 0 34620 1780 840 S 0.3 0.2 0:29.20 redis-server
1 root 20 0 24340 2180 1284 S 0.0 0.2 0:00.42 init
2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:02.34 ksoftirqd/0
6 root rt 0 0 0 0 S 0.0 0.0 0:00.00 migration/0
7 root rt 0 0 0 0 S 0.0 0.0 0:00.35 watchdog/0
8 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 cpuset
9 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 khelper
10 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kdevtmpfs
11 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 netns
12 root 20 0 0 0 0 S 0.0 0.0 0:00.16 sync_supers
13 root 20 0 0 0 0 S 0.0 0.0 0:00.00 bdi-default
14 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kintegrityd
15 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kblockd
16 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ata_sff
17 root 20 0 0 0 0 S 0.0 0.0 0:00.00 khubd
18 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 md
20 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kworker/u:1
21 root 20 0 0 0 0 S 0.0 0.0 0:00.01 khungtaskd
22 root 20 0 0 0 0 S 0.0 0.0 0:00.09 kswapd0
23 root 25 5 0 0 0 S 0.0 0.0 0:00.00 ksmd
24 root 39 19 0 0 0 S 0.0 0.0 0:00.00 khugepaged
25 root 20 0 0 0 0 S 0.0 0.0 0:00.00 fsnotify_mark
26 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ecryptfs-kthrea
27 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 crypto
36 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kthrotld
37 root 20 0 0 0 0 S 0.0 0.0 0:00.00 scsi_eh_0
38 root 20 0 0 0 0 S 0.0 0.0 0:00.00 scsi_eh_1
40 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 binder
41 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kworker/u:3
60 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 deferwq
61 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 charger_manager
62 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 devfreq_wq
210 root 20 0 0 0 0 S 0.0 0.0 0:05.12 jbd2/sda-8
212 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 ext4-dio-unwrit
294 root 20 0 17232 640 452 S 0.0 0.1 0:00.05 upstart-udev-br
296 root 20 0 21600 1316 760 S 0.0 0.1 0:00.03 udevd
363 messageb 20 0 23924 1120 804 S 0.0 0.1 0:00.01 dbus-daemon
370 syslog 20 0 243m 1384 1064 S 0.0 0.1 0:00.22 rsyslogd
448 root 20 0 21596 780 220 S 0.0 0.1 0:00.00 udevd
449 root 20 0 21596 844 284 S 0.0 0.1 0:00.00 udevd
537 root 20 0 49972 2792 2200 S 0.0 0.3 0:00.05 sshd
540 root 0 -20 0 0 0 S 0.0 0.0 0:00.00 kpsmoused
587 root 20 0 15188 392 200 S 0.0 0.0 0:00.00 upstart-socket-
619 root 20 0 15784 948 784 S 0.0 0.1 0:00.00 getty
623 root 20 0 15784 952 784 S 0.0 0.1 0:00.00 getty
630 root 20 0 15784 952 784 S 0.0 0.1 0:00.00 getty
632 root 20 0 15784 948 784 S 0.0 0.1 0:00.00 getty
634 root 20 0 15784 952 784 S 0.0 0.1 0:00.00 getty
644 root 20 0 4332 680 544 S 0.0 0.1 0:00.00 acpid
645 root 20 0 19112 992 748 S 0.0 0.1 0:00.07 cron
646 daemon 20 0 16908 160 0 S 0.0 0.0 0:00.00 atd
723 postgres 20 0 127m 10m 8916 S 0.0 1.0 0:01.20 postgres
748 postgres 20 0 127m 2188 776 S 0.0 0.2 0:07.56 postgres
749 postgres 20 0 127m 1696 308 S 0.0 0.2 0:07.29 postgres
750 postgres 20 0 127m 3092 1044 S 0.0 0.3 0:02.07 postgres
751 postgres 20 0 98560 1808 320 S 0.0 0.2 0:02.51 postgres
774 root 20 0 215m 1900 1644 S 0.0 0.2 0:00.00 PassengerWatchd
777 root 20 0 549m 3504 2248 S 0.0 0.3 1:16.02 PassengerHelper
779 root 20 0 109m 9964 2420 S 0.0 1.0 0:00.11 ruby
782 nobody 20 0 165m 4480 3460 S 0.0 0.4 0:00.15 PassengerLoggin
814 root 20 0 37428 1040 220 S 0.0 0.1 0:00.00 nginx

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RES – Resident size (kb) <br>The non-swapped physical memory a task has used. <br>RES = CODE + DATA. <br> <br>VIRT – Virtual Image (kb) <br>The total amount of virtual memory used by the task. It includes all code, data and shared libraries plus pages that have been swapped out. <br>VIRT = SWAP + RES. <br> <br>So the resident memory usage is the one you want to pay more attention to but with databases don’t forget they also have a lot of internal caching even if you don’t tune them as they will like to cache various requests, indexes, and have other temporary tables that they use to return queries faster. Often without specifying specific limits they can begin to use most of the available system memory since if it is completely unallocated why not use it to perform a function.

The first I’d suggest to google for “understanding top command output”. <br>P.S. No way I meant “let me google for you” :)