在/proc/meminfo，据我所知
缓存 >= 映射
但之后/proc/sys/vm/drop_caches，它转到
缓存 < 映射
Cached: 66132 kB
Mapped: 67792 kB
/proc/meminfo之后的内容：
MemTotal: 369020 kB
MemFree: 34588 kB
Buffers: 184 kB
Cached: 66132 kB
SwapCached: 0 kB
Active: 246624 kB
Inactive: 29688 kB
Active(anon): 209728 kB
Inactive(anon): 9920 kB
Active(file): 36896 kB
Inactive(file): 19768 kB
Unevictable: 12 kB
Mlocked: 12 kB
HighTotal: 0 kB
HighFree: 0 kB
LowTotal: 369020 kB
LowFree: 34588 kB
SwapTotal: 0 kB
SwapFree: 0 kB
Dirty: 4 kB
Writeback: 0 kB
AnonPages: 210040 kB
Mapped: 67792 kB
Shmem: 9644 kB
Slab: 27520 kB
SReclaimable: 7500 kB
SUnreclaim: 20020 kB
KernelStack: 3160 kB
PageTables: 5004 kB
NFS_Unstable: 0 kB
Bounce: 0 kB
WritebackTmp: 0 kB
CommitLimit: 184508 kB
Committed_AS: 1832660 kB
VmallocTotal: 499712 kB
VmallocUsed: 2708 kB
VmallocChunk: 417128 kB
有人知道这个问题吗？