To Clear Linux Memory Cache

To free pagecache:

# sync; echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:

# sync; echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:

# sync; echo 3 > /proc/sys/vm/drop_caches

==> sync - flush file system buffers