Why my Linux vps's memory use a lot?

Question

Total memory is 1 Gb. I only run 2 websites on it! But it's all used. How can i free some memory ? restart the server will work for a while. The websites are using wordpress.

These are all the processes:

USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root         1  0.0  0.0   2160   648 ?        Ss   Nov30   0:02 init [3]
root         2  0.0  0.0      0     0 ?        S<   Nov30   0:09 [migration/0]
root         3  0.0  0.0      0     0 ?        SN   Nov30   0:00 [ksoftirqd/0]
root         4  0.0  0.0      0     0 ?        S<   Nov30   0:00 [watchdog/0]
root         5  0.0  0.0      0     0 ?        S<   Nov30   0:06 [migration/1]
root         6  0.0  0.0      0     0 ?        SN   Nov30   0:00 [ksoftirqd/1]
root         7  0.0  0.0      0     0 ?        S<   Nov30   0:00 [watchdog/1]
root         8  0.0  0.0      0     0 ?        S<   Nov30   0:01 [events/0]
root         9  0.0  0.0      0     0 ?        S<   Nov30   0:01 [events/1]
root        10  0.0  0.0      0     0 ?        S<   Nov30   0:00 [khelper]
root        11  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kthread]
root        15  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kblockd/0]
root        16  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kblockd/1]
root        17  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kacpid]
root       120  0.0  0.0      0     0 ?        S<   Nov30   0:00 [cqueue/0]
root       121  0.0  0.0      0     0 ?        S<   Nov30   0:00 [cqueue/1]
root       124  0.0  0.0      0     0 ?        S<   Nov30   0:00 [khubd]
root       126  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kseriod]
root       192  0.0  0.0      0     0 ?        S    Nov30   0:00 [khungtaskd]
root       193  0.0  0.0      0     0 ?        S    Nov30   0:02 [pdflush]
root       195  0.0  0.0      0     0 ?        S<   Nov30   0:01 [kswapd0]
root       196  0.0  0.0      0     0 ?        S<   Nov30   0:00 [aio/0]
root       197  0.0  0.0      0     0 ?        S<   Nov30   0:00 [aio/1]
root       350  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kpsmoused]
root       395  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ata/0]
root       396  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ata/1]
root       397  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ata_aux]
root       407  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kstriped]
root       420  0.0  0.0      0     0 ?        S<   Nov30   0:11 [kjournald]
root       450  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kauditd]
root       483  0.0  0.1   3012  1404 ?        S<s  Nov30   0:00 /sbin/udevd -d
root       797  0.0  0.0      0     0 ?        S    Dec02   0:01 [pdflush]
root       836  0.0  0.0      0     0 ?        S<   Nov30   0:00 [vballoon]
root      1131  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kmpathd/0]
root      1132  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kmpathd/1]
root      1133  0.0  0.0      0     0 ?        S<   Nov30   0:00 [kmpath_handlerd]
root      1403  0.0  0.0      0     0 ?        S<   Nov30   0:00 [iscsi_eh]
root      1455  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ib_addr]
root      1465  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ib_mcast]
root      1467  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ib_inform]
root      1468  0.0  0.0      0     0 ?        S<   Nov30   0:00 [local_sa]
root      1472  0.0  0.0      0     0 ?        S<   Nov30   0:00 [iw_cm_wq]
root      1476  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ib_cm/0]
root      1477  0.0  0.0      0     0 ?        S<   Nov30   0:00 [ib_cm/1]
root      1481  0.0  0.0      0     0 ?        S<   Nov30   0:00 [rdma_cm]
root      1497  0.0  0.0  22456   424 ?        Ssl  Nov30   0:00 brcm_iscsiuio
root      1503  0.0  0.0   3700   448 ?        Ss   Nov30   0:01 iscsid
root      1504  0.0  0.4   4156  4152 ?        S<Ls Nov30   0:03 iscsid
root      1596  0.0  0.0   2264   512 ?        Ss   Nov30   0:01 mcstransd
root      1829  0.0  0.0   2404   728 ?        Ss   Nov30   0:05 /sbin/dhclient -1 -q -lf /var/lib/dhclient/dhclient-eth0.leases -pf /var/run/dhclien
root      1881  0.0  0.0  12656   812 ?        S<sl Nov30   0:01 auditd
root      1883  0.0  0.0  13196   812 ?        S<sl Nov30   0:00 /sbin/audispd
root      1904  0.0  1.0  12340 10672 ?        Ss   Nov30   0:00 /usr/sbin/restorecond
root      1917  0.0  0.0   1920   696 ?        Ss   Nov30   0:05 syslogd -m 0
root      1920  0.0  0.0   1764   408 ?        Ss   Nov30   0:00 klogd -x
root      1982  0.0  0.0   2560   384 ?        Ss   Nov30   0:04 irqbalance
rpc       2013  0.0  0.0   1912   556 ?        Ss   Nov30   0:00 portmap
root      2043  0.0  0.0      0     0 ?        S<   Nov30   0:00 [rpciod/0]
root      2044  0.0  0.0      0     0 ?        S<   Nov30   0:00 [rpciod/1]
root      2052  0.0  0.0   2068   836 ?        Ss   Nov30   0:00 rpc.statd
root      2084  0.0  0.0   5944   648 ?        Ss   Nov30   0:00 rpc.idmapd
dbus      2107  0.0  0.1  13188  1272 ?        Ssl  Nov30   0:03 dbus-daemon --system
root      2123  0.0  1.3  46096 14200 ?        Ssl  Nov30   0:42 /usr/bin/python -E /usr/sbin/setroubleshootd
root      2136  0.0  0.0   2256   768 ?        Ss   Nov30   0:00 /usr/sbin/hcid
root      2142  0.0  0.0   1832   504 ?        Ss   Nov30   0:00 /usr/sbin/sdpd
root      2165  0.0  0.0      0     0 ?        S<   Nov30   0:00 [krfcommd]
root      2211  0.0  0.1  12828  1348 ?        Ssl  Nov30   0:18 pcscd
root      2225  0.0  0.0   1760   540 ?        Ss   Nov30   0:00 /usr/sbin/acpid
68        2242  0.0  0.3   5788  3756 ?        Ss   Nov30   0:00 hald
root      2243  0.0  0.0   3264  1008 ?        S    Nov30   0:00 hald-runner
68        2250  0.0  0.0   2108   820 ?        S    Nov30   0:00 hald-addon-acpi: listening on acpid socket /var/run/acpid.socket
68        2260  0.0  0.0   2108   816 ?        S    Nov30   0:00 hald-addon-keyboard: listening on /dev/input/event0
root      2285  0.0  0.0   2008   452 ?        Ss   Nov30   0:00 /usr/bin/hidd --server
root      2323  0.0  0.1  29416  1376 ?        Ssl  Nov30   0:03 automount
root      2380  0.0  0.1   9384  1908 ?        Ss   Nov30   0:01 sendmail: accepting connections
smmsp     2421  0.0  0.1   8292  1512 ?        Ss   Nov30   0:00 sendmail: Queue runner@01:00:00 for /var/spool/clientmqueue
root      2435  0.0  0.0   2000   372 ?        Ss   Nov30   0:00 gpm -m /dev/input/mice -t exps2
root      2448  0.0  0.1   5380  1200 ?        Ss   Nov30   0:00 crond
xfs       2475  0.0  0.1   3640  1252 ?        Ss   Nov30   0:00 xfs -droppriv -daemon
root      2500  0.0  0.0   2360   448 ?        Ss   Nov30   0:00 /usr/sbin/atd
avahi     2526  0.0  0.1   2696  1280 ?        Ss   Nov30   0:00 avahi-daemon: running [584be59e-9224-4d49-9768-35da3a6fc524.local]
avahi     2527  0.0  0.0   2696   324 ?        Ss   Nov30   0:00 avahi-daemon: chroot helper
root      2559  0.0  0.0   3612   444 ?        S    Nov30   0:00 /usr/sbin/smartd -q never
root      2562  0.0  0.0   1748   444 tty1     Ss+  Nov30   0:00 /sbin/mingetty tty1
root      2563  0.0  0.0   1748   448 tty2     Ss+  Nov30   0:00 /sbin/mingetty tty2
root      2564  0.0  0.0   1748   448 tty3     Ss+  Nov30   0:00 /sbin/mingetty tty3
root      2565  0.0  0.0   1748   476 tty4     Ss+  Nov30   0:00 /sbin/mingetty tty4
root      2566  0.0  0.0   1748   452 tty5     Ss+  Nov30   0:00 /sbin/mingetty tty5
root      2567  0.0  0.0   1748   448 tty6     Ss+  Nov30   0:00 /sbin/mingetty tty6
root      2619  0.0  1.0  26928 11252 ?        SN   Nov30   0:11 /usr/bin/python -tt /usr/sbin/yum-updatesd
root      2621  0.0  0.1   2656  1156 ?        SN   Nov30   0:02 /usr/libexec/gam_server
root      3356  0.0  0.0      0     0 ?        S<   Dec02   0:00 [kjournald]
root     15559  0.0  0.1   7208  1060 ?        Ss   Dec02   0:00 /usr/sbin/sshd
root     18495  0.0  1.0  30280 10356 ?        Ss   Dec02   0:00 /usr/sbin/httpd
apache   18497  0.1  2.1  42460 21772 ?        S    Dec02   1:49 /usr/sbin/httpd
apache   18498  0.1  2.0  42180 21520 ?        S    Dec02   1:43 /usr/sbin/httpd
apache   18499  0.1  2.1  42456 22352 ?        S    Dec02   1:36 /usr/sbin/httpd
apache   18500  0.1  3.4  55232 35384 ?        S    Dec02   1:45 /usr/sbin/httpd
apache   18501  0.1  2.0  42156 21500 ?        S    Dec02   1:47 /usr/sbin/httpd
apache   18502  0.1  3.3  54164 34260 ?        S    Dec02   1:41 /usr/sbin/httpd
apache   18503  0.1  3.1  53292 32616 ?        S    Dec02   1:37 /usr/sbin/httpd
apache   18504  0.1  2.0  41916 21236 ?        S    Dec02   1:40 /usr/sbin/httpd
root     19229  0.0  0.1   4628  1224 ?        S    Dec02   0:00 /bin/sh /usr/bin/mysqld_safe --datadir=/var/lib/mysql --socket=/var/lib/mysql/mysql.
mysql    19311  0.1  2.8 141324 29036 ?        Sl   Dec02   1:24 /usr/libexec/mysqld --basedir=/usr --datadir=/var/lib/mysql --user=mysql --pid-file=
apache   20725  0.1  2.0  41976 21276 ?        S    Dec02   1:32 /usr/sbin/httpd
apache   20726  0.1  3.0  51884 31992 ?        S    Dec02   1:39 /usr/sbin/httpd
apache   20727  0.1  2.9  51508 30784 ?        S    Dec02   1:36 /usr/sbin/httpd
root     26598  0.1  1.0  17884 11104 ?        Rs   11:04   0:00 sshd: root@pts/0
root     26633  0.0  0.1   4632  1444 pts/0    Ss   11:04   0:00 -bash
root     26906  0.0  0.1   4888  1640 ?        S    11:10   0:00 /bin/bash /sbin/dhclient-script
root     26917  0.0  0.0   4352   960 pts/0    R+   11:10   0:00 ps -aux

Answer 1

Nothing looks terribly unhealthy from your ps output. Keep in mind that the Linux kernel LOVES cache and will cache as much as it can in memory. As long as you're not swapping memory to disk you should be okay. Are you seeing any ill effects?

If you believe your memory utilization is indeed a problem look in to your Apache thread pool and allocations as well as your mysqld innodb buffer pools.

http://httpd.apache.org/docs/2.2/misc/perf-tuning.html http://dev.mysql.com/doc/refman/5.5/en/innodb-buffer-pool.html