diff --git a/sys/kern/subr_blist.c b/sys/kern/subr_blist.c
index 3f8f1771d66..f7e431a0513 100644
--- a/sys/kern/subr_blist.c
+++ b/sys/kern/subr_blist.c
@@ -278,6 +278,14 @@ blist_destroy(blist_t bl)
 	free(bl, M_SWAP);
 }
 
+#include <sys/sysctl.h>
+static SYSCTL_NODE(_debug, OID_AUTO, counters, CTLFLAG_RD, 0, "");
+
+static long alloc_success, alloc_failure, avg_count, count_err;
+SYSCTL_ULONG(_debug_counters, OID_AUTO, alloc_success, CTLFLAG_RD, &alloc_success, 0, "");
+SYSCTL_ULONG(_debug_counters, OID_AUTO, alloc_failure, CTLFLAG_RD, &alloc_failure, 0, "");
+SYSCTL_ULONG(_debug_counters, OID_AUTO, avg_count, CTLFLAG_RD, &avg_count, 0, "");
+
 /*
  * blist_alloc() -   reserve space in the block bitmap.  Return the base
  *		     of a contiguous region or SWAPBLK_NONE if space could
@@ -297,6 +305,9 @@ blist_alloc(blist_t bl, daddr_t count)
 	 * non-zero.  When the cursor is zero, an allocation failure will
 	 * stop further iterations.
 	 */
+	count_err += count - avg_count;
+	avg_count += count_err / (alloc_success + alloc_failure + 1);
+	count_err %= alloc_success + alloc_failure + 1;
 	for (;;) {
 		blk = blst_meta_alloc(bl->bl_root, bl->bl_cursor, count,
 		    bl->bl_radix);
@@ -305,9 +316,12 @@ blist_alloc(blist_t bl, daddr_t count)
 			bl->bl_cursor = blk + count;
 			if (bl->bl_cursor == bl->bl_blocks)
 				bl->bl_cursor = 0;
+			alloc_success++;
 			return (blk);
-		} else if (bl->bl_cursor == 0)
+		} else if (bl->bl_cursor == 0) {
+			alloc_failure++;
 			return (SWAPBLK_NONE);
+		}
 		bl->bl_cursor = 0;
 	}
 }