Release Cache Memory

Linux 從 kernel 2.6.16 開始，提供透過指令清除 pagecache、inode、dentry。

$ sync; /sbin/sysctl vm.drop_caches=3

或者
$ sync; echo 3 > /proc/sys/vm/drop_caches

查看清除前的記憶體使用情況
$ cat /proc/meminfo
MemTotal: 10270912 kB
MemFree: 33092 kB
Buffers: 152300 kB
Cached: 9784508 kB
SwapCached: 0 kB
Active: 196180 kB
Inactive: 9802104 kB
SwapTotal: 2031608 kB
SwapFree: 2031608 kB


查看清除後的記憶體使用情況
$ cat /proc/meminfo
MemTotal: 10270912 kB
MemFree: 10061932 kB
Buffers: 408 kB
Cached: 28692 kB
SwapCached: 0 kB
Active: 89624 kB
Inactive: 928 kB
SwapTotal: 2031608 kB
SwapFree: 2031608 kB


參考資料
drop_caches, http://www.linuxinsight.com/proc_sys_vm_drop_caches.html
The Linux Kernel Archives - vm sysctl documentation, http://www.kernel.org/doc/Documentation/sysctl/vm.txt