解決free -h cached 過大 問題

//先同步數據
sync 

//cache 釋放：
//To free pagecache:
echo 1 > /proc/sys/vm/drop_caches

//To free dentries and inodes:
echo 2 > /proc/sys/vm/drop_caches

//To free pagecache, dentries and inodes:
echo 3 > /proc/sys/vm/drop_caches