diff --git a/sys/kern/vfs_subr.c b/sys/kern/vfs_subr.c
--- a/sys/kern/vfs_subr.c
+++ b/sys/kern/vfs_subr.c
@@ -757,15 +757,15 @@
 	int cpu, physvnodes, virtvnodes;
 
 	/*
-	 * Desiredvnodes is a function of the physical memory size and the
-	 * kernel's heap size.  Generally speaking, it scales with the
-	 * physical memory size.  The ratio of desiredvnodes to the physical
-	 * memory size is 1:16 until desiredvnodes exceeds 98,304.
-	 * Thereafter, the
-	 * marginal ratio of desiredvnodes to the physical memory size is
-	 * 1:64.  However, desiredvnodes is limited by the kernel's heap
-	 * size.  The memory required by desiredvnodes vnodes and vm objects
-	 * must not exceed 1/10th of the kernel's heap size.
+	 * 'desiredvnodes' is the minimum of a function of the physical memory
+	 * size and another of the kernel heap size (UMA limit, a portion of the
+	 * KVA).
+	 *
+	 * Currently, on 64-bit platforms, 'desiredvnodes' is set to
+	 * 'virtvnodes' up to a physical memory cutoff of ~1674MB, after which
+	 * 'physvnodes' applies instead.  With the current automatic tuning for
+	 * 'maxfiles' (32 files/MB), 'desiredvnodes' becomes smaller than it at
+	 * ~5136MB.
 	 */
 	physvnodes = maxproc + pgtok(vm_cnt.v_page_count) / 64 +
 	    3 * min(98304 * 16, pgtok(vm_cnt.v_page_count)) / 64;