Home / server / Questions / 411866
In Process
Sander
Asked: 2012-07-28 06:59:23 +0800 CST

Why is my VPS is using 4.5GB of RAM, even if no services are running?

  • 772

My VPS is using much RAM. To identify the problem I stopped literally every service, the VPS is still using 4.5GB of RAM. The VPS is running on XEN, so the RAM is not shared.

This is the output of free -m after stopping all services (except ssh):

[root@node3 ~]# free -m

             total used free shared buffers cached

Mem:          6928 5510 1417 0 130 704

-/+ buffers/cache: 4676 2251

Swap:         3071 106 2965

Could someone help me with this? Many thanks.

[root@node3 custombuild]# ps aux | sort -b -k 4 | tail
acusu161  307520  0.0  0.0  94344  1828 ?        SN   14:42   0:00 sshd: acusu161@pts/2
root      301805  0.0  0.0  94344  3352 ?        SNs  14:19   0:00 sshd: acusu161 [priv]
root      307459  0.0  0.0  94344  3360 ?        SNs  14:41   0:00 sshd: acusu161 [priv]
acusu161  301833  0.0  0.0  94484  1896 ?        SN   14:19   0:00 sshd: acusu161@pts/1
acusu161  328664  0.0  0.0  95128  1748 ?        SN   16:24   0:00 sshd: acusu161@pts/4
root      328660  0.0  0.0  95128  3348 ?        SNs  16:24   0:00 sshd: acusu161 [priv]
named      10398  0.0  0.1 589860  7896 ?        Ssl  Jul23   0:02 named -u named
root      340628  0.0  0.3 127764 26884 ?        SNs  16:48   0:01 lfd - sleeping
root        6508  0.0  0.4  38936 32788 ?        S<Lsl Jul23   0:00 iscsiuio
USER         PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
linux

2 Answers

  1. It's nothing to worry about, linux likes to cache things, the cache will be overwritten when new processes ask for the memory.

    You can clear it. ymmv.

       sudo sync && sudo sysctl -w vm.drop_caches=3 && sudo sysctl -w vm.drop_caches=0

    source: http://duopetalflower.blogspot.ca/2009/09/clearing-cache-memory-in-linux-using.html

       free && sync && echo 3 > /proc/sys/vm/drop_caches && free

    source: http://www.commandlinefu.com/commands/view/1026/empty-the-linux-buffer-cache

    To free pagecache:
        echo 1 > /proc/sys/vm/drop_caches
To free dentries and inodes:
        echo 2 > /proc/sys/vm/drop_caches
To free pagecache, dentries and inodes:
        echo 3 > /proc/sys/vm/drop_caches

    source: https://stackoverflow.com/questions/8066252/invalid-argument-error-for-sysctl-vm-drop-caches-key-in-ubuntu-11-10-kernel-3

    • 2

  2. Try installing an utility such as "htop" and sorting (F6) by memory usage (MEM%) to see which processes are using how much memory.

    • 0