내 RAM은 다 어디로 갔나요?

RHEVM 서버에서 free -m 명령을 실행하면 23117MB의 "used - (buffer+cache)" RAM이 사용 중이고 무료 "free + (buffer+cache)"는 9120MB라고 표시됩니다.

사용 가능한 총 RAM은 30759MB, 실제 사용된 RAM은 23117MB, 실제 사용 가능한 RAM은 9120MB입니다.

RAM을 소비하는 프로세스를 찾으려고 했더니 POSTMASTER 프로세스였지만 여전히 1288MB만 사용했습니다.

이것은 최상위 프로세스 목록입니다.

1288MB  postmaster
859MB   java
449MB   udisks-daemon
355MB   gnome-settings-
232MB   firefox
133MB   httpd
132MB   gpk-update-icon
58MB    gdu-notificatio
55MB    gvfs-gdu-volume
42MB    python
38MB    nautilus
29MB    Xorg
24MB    Xvnc
24MB    clock-applet
19MB    sshd
13MB    gnome-panel
13MB    metacity
12MB    mdmon
12MB    gnome-session
12MB    wnck-applet
11MB    gnome-volume-co
11MB    ovirt-engine.py
11MB    gdm-user-switch
10MB    notification-da

TOP 명령의 출력

Tasks: 371 total,   1 running, 370 sleeping,   0 stopped,   0 zombie
Cpu(s):  0.7%us,  0.3%sy,  0.0%ni, 98.7%id,  0.2%wa,  0.0%hi,  0.0%si,  0.0%st
Mem:  32853828k total, 31500888k used,  1352940k free,   208496k buffers
Swap: 16777208k total,   561144k used, 16216064k free,  7620628k cached

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
 2780 ovirt     20   0 5924m 858m  21m S  2.7  2.7   4:58.50 java
  130 root      39  19     0    0    0 S  1.0  0.0  10704:56 kipmi0
  472 root      20   0     0    0    0 S  0.3  0.0   3533:58 md126_raid1
 1778 root      20   0     0    0    0 S  0.3  0.0 288:47.88 kondemand/1
 2992 postgres  20   0  270m  62m  11m S  0.3  0.2   0:19.17 postmaster
 2993 postgres  20   0  269m  62m  11m S  0.3  0.2   0:19.27 postmaster
 2994 postgres  20   0  271m  65m  11m S  0.3  0.2   0:19.38 postmaster
 2996 postgres  20   0  270m  63m  11m S  0.3  0.2   0:19.16 postmaster
 3042 postgres  20   0  272m  63m  11m S  0.3  0.2   0:19.27 postmaster
 3043 postgres  20   0  270m  66m  11m S  0.3  0.2   0:18.88 postmaster
 3056 postgres  20   0  269m  60m  11m S  0.3  0.2   0:18.96 postmaster
 3057 postgres  20   0  269m  62m  11m S  0.3  0.2   0:18.85 postmaster
 3058 postgres  20   0  270m  64m  11m S  0.3  0.2   0:19.00 postmaster
 3062 postgres  20   0  272m  63m  11m S  0.3  0.2   0:18.96 postmaster
 4744 root 20   0 15280 1472  948 R  0.3  0.0   0:00.02 top
    1 root      20   0 19364 1224 1016 S  0.0  0.0   0:13.54 init
    2 root      20   0     0    0    0 S  0.0  0.0   0:07.08 kthreadd
    3 root      RT   0     0    0    0 S  0.0  0.0   0:57.27 migration/0
    4 root      20   0     0    0    0 S  0.0  0.0   4:43.07 ksoftirqd/0
    5 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/0
    6 root      RT   0     0    0    0 S  0.0  0.0   0:49.55 watchdog/0
    7 root      RT   0     0    0    0 S  0.0  0.0   0:55.62 migration/1
    8 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/1
    9 root      20   0     0    0    0 S  0.0  0.0  14:32.43 ksoftirqd/1
   10 root      RT   0     0    0    0 S  0.0  0.0   0:41.13 watchdog/1
   11 root      RT   0     0    0    0 S  0.0  0.0   0:41.82 migration/2
   12 root      RT   0     0    0    0 S  0.0  0.0   0:00.00 migration/2
   13 root      20   0     0    0    0 S  0.0  0.0   4:40.52 ksoftirqd/2

자유로운 명령 출력

             total       used       free     shared    buffers     cached
Mem:         32083      30999       1084          0        204       7665
-/+ buffers/cache:      23129       8954
Swap:        16383        547      15836

23117MB RAM은 어떤 용도로 사용되나요?