This function returns 0 on success or -1 on error.
+=head2 guestfs_drop_caches
+
+ int guestfs_drop_caches (guestfs_h *handle,
+ int whattodrop);
+
+This instructs the guest kernel to drop its page cache,
+and/or dentries and inode caches. The parameter C<whattodrop>
+tells the kernel what precisely to drop, see
+L<http://linux-mm.org/Drop_Caches>
+
+Setting C<whattodrop> to 3 should drop everything.
+
+This automatically calls L<sync(2)> before the operation,
+so that the maximum guest memory is freed.
+
+This function returns 0 on success or -1 on error.
+
=head2 guestfs_exists
int guestfs_exists (guestfs_h *handle,