Index: sys/kern/vfs_subr.c
===================================================================
--- sys/kern/vfs_subr.c
+++ sys/kern/vfs_subr.c
@@ -322,11 +322,14 @@
 	 * size.  The memory required by desiredvnodes vnodes and vm objects
 	 * may not exceed one seventh of the kernel's heap size.
 	 */
-	physvnodes = maxproc + cnt.v_page_count / 16 + 3 * min(98304 * 4,
-	    cnt.v_page_count) / 16;
-	virtvnodes = vm_kmem_size / (7 * (sizeof(struct vm_object) +
-	    sizeof(struct vnode)));
-	desiredvnodes = min(physvnodes, virtvnodes);
+	TUNABLE_INT_FETCH("kern.maxvnodes", &desiredvnodes);
+	if (desiredvnodes == 0) {
+		physvnodes = maxproc + cnt.v_page_count / 16 + 3 *
+		    min(98304 * 4, cnt.v_page_count) / 16;
+		virtvnodes = vm_kmem_size / (7 * (sizeof(struct vm_object) +
+		    sizeof(struct vnode)));
+		desiredvnodes = min(physvnodes, virtvnodes);
+	}
 	if (desiredvnodes > MAXVNODES_MAX) {
 		if (bootverbose)
 			printf("Reducing kern.maxvnodes %d -> %d\n",