Index: branches/freebsd10/src/sys/kern/subr_disk.c
===================================================================
diff -u -N -r2284 -r2698
--- branches/freebsd10/src/sys/kern/subr_disk.c	(.../subr_disk.c)	(revision 2284)
+++ branches/freebsd10/src/sys/kern/subr_disk.c	(.../subr_disk.c)	(revision 2698)
@@ -21,8 +21,13 @@
 #include <sys/bio.h>
 #include <sys/conf.h>
 #include <sys/disk.h>
+#include <sys/sysctl.h>
 #include <geom/geom_disk.h>
 
+static int bioq_batchsize = 128;
+SYSCTL_INT(_debug, OID_AUTO, bioq_batchsize, CTLFLAG_RW,
+    &bioq_batchsize, 0, "BIOQ batch size");
+
 /*-
  * Disk error is the preface to plaintive error messages
  * about failing disk transfers.  It prints messages of the form
@@ -150,6 +155,8 @@
 	TAILQ_INIT(&head->queue);
 	head->last_offset = 0;
 	head->insert_point = NULL;
+	head->total = 0;
+	head->batched = 0;
 }
 
 void
@@ -163,6 +170,7 @@
 		head->insert_point = NULL;
 
 	TAILQ_REMOVE(&head->queue, bp, bio_queue);
+	head->total--;
 }
 
 void
@@ -181,13 +189,16 @@
 	if (head->insert_point == NULL)
 		head->last_offset = bp->bio_offset;
 	TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
+	head->total++;
 }
 
 void
 bioq_insert_tail(struct bio_queue_head *head, struct bio *bp)
 {
 
 	TAILQ_INSERT_TAIL(&head->queue, bp, bio_queue);
+	head->total++;
+	head->batched = 0;
 	head->insert_point = bp;
 	head->last_offset = bp->bio_offset;
 }
@@ -246,6 +257,11 @@
 		return;
 	}
 
+	if (bioq_batchsize > 0 && head->batched > bioq_batchsize) {
+		bioq_insert_tail(head, bp);
+		return;
+	}
+
 	prev = NULL;
 	key = bioq_bio_key(head, bp);
 	cur = TAILQ_FIRST(&head->queue);
@@ -264,4 +280,7 @@
 		TAILQ_INSERT_HEAD(&head->queue, bp, bio_queue);
 	else
 		TAILQ_INSERT_AFTER(&head->queue, prev, bp, bio_queue);
+
+	head->total++;
+	head->batched++;
 }
Index: branches/freebsd10/src/sys/sys/bio.h
===================================================================
diff -u -N -r2284 -r2698
--- branches/freebsd10/src/sys/sys/bio.h	(.../bio.h)	(revision 2284)
+++ branches/freebsd10/src/sys/sys/bio.h	(.../bio.h)	(revision 2698)
@@ -129,6 +129,8 @@
 	TAILQ_HEAD(bio_queue, bio) queue;
 	off_t last_offset;
 	struct	bio *insert_point;
+	int total;
+	int batched;
 };
 
 extern struct vm_map *bio_transient_map;