산이님 답변대로 해서 내용을 복사해서 올립니다.

[root@localhost root]# cat /proc/meminfo 
        total:    used:    free:  shared: buffers:  cached:
Mem:  328171520 149626880 178544640        0 33722368 46096384
Swap: 830742528        0 830742528
MemTotal:       320480 kB
MemFree:        174360 kB
MemShared:           0 kB
Buffers:         32932 kB
Cached:          45016 kB
SwapCached:          0 kB
Active:          82356 kB
Inact_dirty:      4784 kB
Inact_clean:      7524 kB
Inact_target:    18932 kB
HighTotal:           0 kB
HighFree:            0 kB
LowTotal:       320480 kB
LowFree:        174360 kB
SwapTotal:      811272 kB
SwapFree:       811272 kB
Committed_AS:    37924 kB

아래는 top 으로 확인한 결과 입니다.

Mem:   320480K av,  146256K used,  174224K free,       0K shrd,   32948K buff
Swap:  811272K av,       0K used,  811272K free                   45016K cached

[root@localhost root]# free -m
             total       used       free     shared    buffers     cached
Mem:           312        142        170          0         32         43
-/+ buffers/cache:         66        246
Swap:          792          0        792

그리고 저는 레드햇 7.3 사용하고 있습니다.