CentOS 7, Memory Hungry (2.5GB) Without User And Heavy Services Running

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Hello,

The last weekend, the VM with CentOS 7
(kernel-3.10.0-327.28.2.el7.x86_64) was running with 2.5GB of used memory, but without users connected, and heavy services running. Three minutes after reboot, the o.s. is running with 114MB used. ┬┐Why the 62% of memory is used if the o.s. does not have an intensive load?

top sorted by memory:

top – 12:55:34 up 8 days, 21:41, 1 user, load average: 0.16, 0.74, 0.49
Tasks: 90 total, 1 running, 89 sleeping, 0 stopped, 0 zombie
%Cpu0 : 0.0 us, 0.0 sy, 0.0 ni,100.0 id, 0.0 wa, 0.0 hi, 0.0 si,
0.0 st KiB Mem : 3882816 total, 310948 free, 2639892 used, 931976 buff/cache KiB Swap: 7815164 total, 7815164 free, 0 used. 825004 avail Mem

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
579 root 20 0 323592 23168 6232 S 0.0 0.6 0:30.07 firewalld
1110 root 20 0 553052 18264 5624 S 0.0 0.5 3:29.65 tuned
720 polkitd 20 0 530364 10900 4736 S 0.0 0.3 0:12.84 polkitd
587 root 20 0 250252 8060 4800 S 0.7 0.2 20:48.88 vmtoolsd
692 root 20 0 436892 7988 6156 S 0.0 0.2 0:12.36
NetworkManager
1 root 20 0 273832 7128 3820 S 0.0 0.2 2:20.92 systemd
577 root 20 0 210456 5488 3708 S 0.0 0.1 0:03.85 abrtd
26833 root 20 0 143008 5436 4148 S 0.0 0.1 0:13.47 sshd
487 root 20 0 46424 5112 2652 S 0.0 0.1 0:02.26
systemd-udevd
592 root 20 0 207976 4480 3124 S 0.0 0.1 0:02.31
abrt-watch-log
1806 postfix 20 0 93512 4088 3028 S 0.0 0.1 0:02.80 qmgr
470 root 20 0 129132 3956 2456 S 0.0 0.1 0:00.02 lvmetad
580 root 20 0 445712 3888 3156 S 0.0 0.1 1:00.74 rsyslogd
26950 postfix 20 0 93328 3848 2840 S 0.0 0.1 0:00.11 pickup
1112 root 20 0 82560 3544 2688 S 0.0 0.1 1:02.99 sshd
26837 root 20 0 116160 2976 1732 S 0.0 0.1 0:01.94 bash
719 root 20 0 53064 2644 2052 S 0.0 0.1 0:00.25
wpa_supplicant
26783 root 20 0 178108 2448 1520 S 0.0 0.1 0:00.07 crond
578 root 20 0 130060 2184 1672 S 0.0 0.1 0:00.66 smartd
1801 root 20 0 93224 2168 1116 S 0.0 0.1 0:11.25 master
27041 root 20 0 157688 2128 1448 R 1.4 0.1 0:00.51 top
581 dbus 20 0 37112 2116 1392 S 0.0 0.1 0:28.27
dbus-daemon
26968 root 20 0 36820 2076 1812 S 0.0 0.1 0:00.69
systemd-journal
608 chrony 20 0 115844 1860 1448 S 0.0 0.0 0:14.59 chronyd
586 root 20 0 26448 1700 1348 S 0.0 0.0 0:46.24
systemd-logind
615 root 20 0 126336 1680 1028 S 0.0 0.0 0:21.39 crond
555 root 16 -4 116724 1604 1208 S 0.0 0.0 0:33.97 auditd
26787 root 20 0 113120 1404 1220 S 0.0 0.0 0:00.05
freshclam-sleep
620 root 20 0 25964 952 752 S 0.0 0.0 0:00.62 atd
18160 root 20 0 110036 816 692 S 0.0 0.0 0:00.18 agetty
601 libstor+ 20 0 8532 780 632 S 0.0 0.0 0:10.61 lsmd
26792 root 20 0 107896 620 528 S 0.0 0.0 0:00.00 sleep
2 root 20 0 0 0 0 S 0.0 0.0 0:00.24 kthreadd
3 root 20 0 0 0 0 S 0.0 0.0 0:06.40
ksoftirqd/0

# netstat -nao Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State Timer tcp 0 0 127.0.0.1:10025 0.0.0.0:*
LISTEN off (0.00/0/0)
tcp 0 0 0.0.0.0:22 0.0.0.0:*
LISTEN off (0.00/0/0)
tcp 0 0 127.0.0.1:25 0.0.0.0:*
LISTEN off (0.00/0/0)
tcp 0 64 ip.ad.dr.ess:22 my.ip.by.myisp:50470
ESTABLISHED on (0.26/0/0)
tcp6 0 0 :::22 :::*
LISTEN off (0.00/0/0)
tcp6 0 0 ::1:25 :::*
LISTEN off (0.00/0/0)
udp 0 0 127.0.0.1:323 0.0.0.0:*
off (0.00/0/0)
udp6 0 0 ::1:323
:::* off (0.00/0/0)
raw6 0 0 :::58 :::*
7 off (0.00/0/0)
Active UNIX domain sockets (servers and established)
Proto RefCnt Flags Type State I-Node Path unix 2 [ ACC ] STREAM LISTENING 9979
/run/lvm/lvmpolld.socket unix 2 [ ACC ] STREAM LISTENING 9988
/run/lvm/lvmetad.socket unix 2 [ ] DGRAM 6664
/run/systemd/notify unix 2 [ ACC ] STREAM LISTENING 17787 private/tlsmgr unix 2 [ ACC ] STREAM LISTENING 17790 private/rewrite unix 2 [ ACC ] STREAM LISTENING 17793 private/bounce unix 2 [ ACC ] STREAM LISTENING 6676
/run/systemd/journal/stdout unix 2 [ ACC ] STREAM LISTENING 17796 private/defer unix 2 [ ACC ] STREAM LISTENING 17799 private/trace unix 5 [ ] DGRAM 6679
/run/systemd/journal/socket unix 2 [ ACC ] STREAM LISTENING 17802 private/verify unix 11 [ ] DGRAM 6681 /dev/log unix 2 [ ACC ] STREAM LISTENING 17805 public/flush unix 2 [ ACC ] STREAM LISTENING 17808 private/proxymap unix 2 [ ACC ] STREAM LISTENING 17811
private/proxywrite unix 2 [ ACC ] STREAM LISTENING 17814 private/smtp

One thought on - CentOS 7, Memory Hungry (2.5GB) Without User And Heavy Services Running

  • –u7sR9ERxu29s0tpX2cQ1t69JLapNSMnki Content-Type: text/plain; charset=utf-8
    Content-Transfer-Encoding: quoted-printable

    CentOS, as well as all versions of Linux, uses buffer and cache with free RAM. You have alomst 1GB of RAM used as buffer/cache in the above top.

    If programs need more memory than ‘free’, it will be taken from the buffer/cache.

    –u7sR9ERxu29s0tpX2cQ1t69JLapNSMnki

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