How Linux manually frees the cache

Inux the command to release memory:
Sync
Echo 1 >/proc/sys/vm/drop_caches

The value of drop_caches can be a number between 0-3 and represents a different meaning:
0: Not released (system default)
1: Free Page cache
2: Release dentries and Inodes
3: Release all Caches

After releasing the memory, change back to let the system automatically allocate memory again.
echo 0 >/proc/sys/vm/drop_caches

Free-m #看内存是否已经释放掉了.

If we need to release all caches, enter the following command:
Echo 3 >/proc/sys/vm/drop_caches

How Linux manually frees the cache