We have a server with 8GB, running mysql, 4 java applications and a small postgres db. We're having some issues with the system paging when running some mysql queries, so in order to see what's going on we ran some commands to see how memory is being used.
Now the problem is that we can't find who is using 4 of our 8 GBs.
Here is the data we have:
[root@server1 ~]# free -mt
total used free shared buffers cached
Mem: 7983 7934 49 0 65 584
-/+ buffers/cache: 7284 699
Swap: 5951 1032 4919
Total: 13935 8966 4968
So it seems there is a very small usage for buffers and cache, so memory should be mainly used for processes:
Top ordered by %MEM gives ( only processes with %MEM > 0.0 )
top - 16:31:00 up 3 days, 16:26, 3 users, load average: 0.51, 0.53, 0.56
Tasks: 153 total, 1 running, 151 sleeping, 0 stopped, 1 zombie
Cpu(s): 9.9%us, 0.6%sy, 0.0%ni, 85.3%id, 4.1%wa, 0.0%hi, 0.2%si, 0.0%st
Mem: 8175264k total, 8126480k used, 48784k free, 70312k buffers
Swap: 6094840k total, 1057440k used, 5037400k free, 595348k cached
PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ DATA nFLT nDRT COMMAND
7377 mysql 15 0 2677m 1.8g 4624 S 3.0 22.7 107:28.89 2.6g 95k 0 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=/var/run/mysqld/my
17836 root 21 0 2472m 1.0g 9872 S 2.3 13.2 11:18.44 2.4g 403 0 /usr/local/jdk1.6.0_25//bin/java -Djava.util.logging.config.file=/tomcat/conf/logging.properties -Drmi
17969 root 18 0 731m 222m 10m S 3.0 2.8 14:06.67 640m 33 0 /java//bin/java -Xms256m -Xmx256m -Xloggc:/var/log/gestorDeTramas.gc -XX:+PrintGCDetails -Dservice.mod
17980 root 21 0 407m 77m 10m S 0.0 1.0 0:04.35 313m 36 0 /java//bin/java -Xms32m -Xmx64m -Xloggc:/var/log/mensajero.gc -XX:+PrintGCDetails -Dservice.mode=rmi -
19866 postgres 15 0 160m 43m 34m S 11.3 0.5 1:51.57 9856 4 0 postgres: postgres mapas 127.0.0.1(46751) idle
24892 postgres 15 0 160m 41m 32m S 0.0 0.5 1:09.97 9804 3 0 postgres: postgres mapas 127.0.0.1(36534) idle
24891 postgres 15 0 160m 40m 31m S 0.0 0.5 0:50.74 9892 1 0 postgres: postgres mapas 127.0.0.1(36533) idle
24886 postgres 15 0 160m 40m 31m S 4.7 0.5 0:51.35 9936 0 0 postgres: postgres mapas 127.0.0.1(36528) idle
23622 postgres 15 0 160m 40m 31m S 0.0 0.5 0:55.42 9952 1 0 postgres: postgres mapas 127.0.0.1(47826) idle
24887 postgres 15 0 160m 40m 31m S 0.0 0.5 0:44.11 9888 2 0 postgres: postgres mapas 127.0.0.1(36529) idle
24880 postgres 16 0 160m 38m 29m S 4.3 0.5 0:42.49 9920 2 0 postgres: postgres mapas 127.0.0.1(36522) idle
24881 postgres 15 0 160m 29m 20m S 12.6 0.4 0:04.66 9948 0 0 postgres: postgres mapas 127.0.0.1(36523) idle
4139 root 34 19 256m 11m 1652 S 0.0 0.1 0:11.58 18m 902 0 /usr/bin/python -tt /usr/sbin/yum-updatesd
So if I add the RES column I get around 3.5GB.
So, the question is, who is using my physical memory? If I add RES + buffers + cache it's around 4GB and the server has 8GB! What can we do to diagnose the server and see who's using the missing ram?
EDIT: The server is a VMware guest.
Also note the mysql process has a LOT of page faults.
More data:
[root@server1 ~]# cat /proc/meminfo
MemTotal: 8175264 kB
MemFree: 47204 kB
Buffers: 63180 kB
Cached: 611144 kB
SwapCached: 513392 kB
Active: 3458724 kB
Inactive: 538952 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 8175264 kB
LowFree: 47204 kB
SwapTotal: 6094840 kB
SwapFree: 5037416 kB
Dirty: 342108 kB
Writeback: 44 kB
AnonPages: 3303684 kB
Mapped: 61352 kB
Slab: 79452 kB
PageTables: 19236 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
CommitLimit: 10182472 kB
Committed_AS: 5778312 kB
VmallocTotal: 34359738367 kB
VmallocUsed: 266052 kB
VmallocChunk: 34359471959 kB
HugePages_Total: 0
HugePages_Free: 0
HugePages_Rsvd: 0
Hugepagesize: 2048 kB
Another way to see how much resident memory the two top processes are using:
[root@server1 ~]# cat /proc/7377/smaps | grep ^Rss | awk '{A+=$2} END{print A}'
1852112
[root@server1 ~]#
[root@server1 ~]# cat /proc/17836/smaps | grep ^Rss | awk '{A+=$2} END{print A}'
1081620
Best Answer
Is the system a vmware guest? If yes, VMware Balloon driver can use some unaccounted memory.