Index: sys/kern/subr_devsw.c
===================================================================
RCS file: /cvsroot/src/sys/kern/subr_devsw.c,v
retrieving revision 1.33
diff -p -u -r1.33 subr_devsw.c
--- sys/kern/subr_devsw.c	5 Sep 2014 05:57:21 -0000	1.33
+++ sys/kern/subr_devsw.c	31 Jan 2016 22:01:44 -0000
@@ -80,6 +80,7 @@ __KERNEL_RCSID(0, "$NetBSD: subr_devsw.c
 #include <sys/cpu.h>
 #include <sys/buf.h>
 #include <sys/reboot.h>
+#include <sys/sdt.h>
 
 #ifdef DEVSW_DEBUG
 #define	DPRINTF(x)	printf x
@@ -730,12 +731,17 @@ bdev_close(dev_t dev, int flag, int devt
 	return rv;
 }
 
+SDT_PROVIDER_DECLARE(io);
+SDT_PROBE_DEFINE1(io, , , start, "struct buf *"/*bp*/);
+
 void
 bdev_strategy(struct buf *bp)
 {
 	const struct bdevsw *d;
 	int mpflag;
 
+	SDT_PROBE(io,,,start, bp, NULL, NULL, NULL, NULL);
+
 	if ((d = bdevsw_lookup(bp->b_dev)) == NULL) {
 		bp->b_error = ENXIO;
 		bp->b_resid = bp->b_bcount;
Index: sys/kern/vfs_bio.c
===================================================================
RCS file: /cvsroot/src/sys/kern/vfs_bio.c,v
retrieving revision 1.258
diff -p -u -r1.258 vfs_bio.c
--- sys/kern/vfs_bio.c	11 Jan 2016 01:22:36 -0000	1.258
+++ sys/kern/vfs_bio.c	31 Jan 2016 22:01:44 -0000
@@ -146,6 +146,7 @@ __KERNEL_RCSID(0, "$NetBSD: vfs_bio.c,v 
 #include <sys/wapbl.h>
 #include <sys/bitops.h>
 #include <sys/cprng.h>
+#include <sys/sdt.h>
 
 #include <uvm/uvm.h>	/* extern struct uvm uvm */
 
@@ -1474,6 +1475,11 @@ buf_drain(int n)
 	return size;
 }
 
+SDT_PROVIDER_DEFINE(io);
+
+SDT_PROBE_DEFINE1(io, , , wait__start, "struct buf *"/*bp*/);
+SDT_PROBE_DEFINE1(io, , , wait__done, "struct buf *"/*bp*/);
+
 /*
  * Wait for operations on the buffer to complete.
  * When they do, extract and return the I/O's error value.
@@ -1485,11 +1491,15 @@ biowait(buf_t *bp)
 	KASSERT(ISSET(bp->b_cflags, BC_BUSY));
 	KASSERT(bp->b_refcnt > 0);
 
+	SDT_PROBE(io,,,wait_start, bp, NULL, NULL, NULL, NULL);
+
 	mutex_enter(bp->b_objlock);
 	while (!ISSET(bp->b_oflags, BO_DONE | BO_DELWRI))
 		cv_wait(&bp->b_done, bp->b_objlock);
 	mutex_exit(bp->b_objlock);
 
+	SDT_PROBE(io,,,wait_done, bp, NULL, NULL, NULL, NULL);
+
 	return bp->b_error;
 }
 
@@ -1528,11 +1538,15 @@ biodone(buf_t *bp)
 	}
 }
 
+SDT_PROBE_DEFINE1(io, , , done, "struct buf *"/*bp*/);
+
 static void
 biodone2(buf_t *bp)
 {
 	void (*callout)(buf_t *);
 
+	SDT_PROBE(io,,,done, bp, NULL, NULL, NULL, NULL);
+
 	mutex_enter(bp->b_objlock);
 	/* Note that the transfer is done. */
 	if (ISSET(bp->b_oflags, BO_DONE))