I am running a small vServer with Debian 9 (stretch) and 2GB RAM.
For a few months I am somehow missing about 500MB RAM and which I cannot find out how they are used.
When I run free -h
total used free shared buff/cache available
Mem: 2.0G 1.0G 482M 66M 511M 764M
Swap: 1.0G 0B 1.0G
I can see that half of the memory is used, about a quarter is used for caches that can be freed if it is needed and the rest is free.
But when I now check my running processes I can only find about 500MB are used by my processes.
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1458 mysql 20 0 927516 359260 0 S 0.0 17.5 108:31.26 mysqld
877 seafile 20 0 258032 94644 4876 S 0.0 4.6 0:22.92 python2.7
460 seafile 20 0 237156 85504 8036 S 0.0 4.2 0:13.14 python2.7
463 seafile 20 0 233096 82236 8956 S 0.0 4.0 0:05.79 python2.7
875 seafile 20 0 244356 81644 5408 S 0.0 4.0 0:19.50 python2.7
461 seafile 20 0 232464 81032 8232 S 0.0 3.9 0:03.58 python2.7
4054 www-data 20 0 374264 54976 45128 S 0.0 2.7 0:07.58 php-fpm7.0
4026 www-data 20 0 372652 54840 44408 S 0.0 2.7 0:10.36 php-fpm7.0
1865 seafile 20 0 1704520 52828 16 S 0.0 2.6 3:45.10 seaf-server
4021 www-data 20 0 370836 48880 40468 S 0.0 2.4 0:10.83 php-fpm7.0
1975 seafile 20 0 129128 47156 1944 S 0.0 2.3 0:02.06 python2.7
21106 netdata 20 0 189412 36600 2660 S 0.3 1.8 16:07.50 netdata
1604 lukas 20 0 107132 34860 2736 S 0.0 1.7 2:07.91 gunicorn
I have no clue where the remaining 500MB Memory are.
I suspected the kernel but running slabtop
shows it uses only about 80MB.
Active / Total Size (% used) : 76599.41K / 79594.40K (96.2%)
I am running netdata on my server, which shows a nice overview of the memory usage per category and indeed it shows my missing 530MB. I played around with the grouping and created a new group called testing
with the following config and it includes my missing memory (in /etc/netdata/apps_groups.conf
)
testing: systemd*
Why does systemd (or something netdata categorizes as systemd) use about a quarter of my memory? After a reboot it uses only 50MB but after some time it always uses about 500MB.