对操作系统来说，Buffers和Cached是已经被使用的(上图Mem:这一行)

MemFree=total-used314952=24946552-24631600

对应用程序来说（上图对应-/+ buffers/cache那一行）

MemFree=buffers+cached+free19536392=152116+19069324+314952

[root@dvrdvs bin] # free              total         used         free       shared      buffers  Mem:        37820        37316          504            0          704 Swap:            0            0            0Total:        37820        37316          504[root@dvrdvs bin] # cat /proc/meminfo MemTotal:          37820 kBMemFree:             500 kBBuffers:             704 kBCached:            12512 kBSwapCached:            0 kBActive:            11516 kBInactive:          11176 kBActive(anon):       9708 kBInactive(anon):     8160 kBActive(file):       1808 kBInactive(file):     3016 kBUnevictable:           0 kBMlocked:               0 kBSwapTotal:             0 kBSwapFree:              0 kBDirty:                 0 kBWriteback:             0 kBAnonPages:          9500 kBMapped:             4452 kBShmem:              8392 kBSlab:               6432 kBSReclaimable:        600 kBSUnreclaim:         5832 kBKernelStack:         592 kBPageTables:          196 kBNFS_Unstable:          0 kBBounce:                0 kBWritebackTmp:          0 kBCommitLimit:       18908 kBCommitted_AS:      88428 kBVmallocTotal:     966656 kBVmallocUsed:       20720 kBVmallocChunk:     918896 kB[root@dvrdvs bin] #

 

 

 

[root@dvrdvs app] # free              total         used         free       shared      buffers  Mem:        38064        23212        14852            0           36 Swap:            0            0            0Total:        38064        23212        14852[root@dvrdvs app] # hik_echo 3 > /proc/sys/vm/drop_caches [root@dvrdvs app] # free              total         used         free       shared      buffers  Mem:        38064        22984        15080            0           32 Swap:            0            0            0Total:        38064        22984        15080[root@dvrdvs app] # cat /proc/cmdline mem=42M console=ttyS0,115200n8 kdbg=7