Index: kern_timeout.c
===================================================================
RCS file: /home/ncvs/src/sys/kern/kern_timeout.c,v
retrieving revision 1.117
diff -u -r1.117 kern_timeout.c
--- kern_timeout.c	13 Jan 2009 15:56:53 -0000	1.117
+++ kern_timeout.c	23 Jan 2009 14:54:51 -0000
@@ -37,6 +37,8 @@
 #include <sys/cdefs.h>
 __FBSDID("$FreeBSD: src/sys/kern/kern_timeout.c,v 1.117 2009/01/13 15:56:53 jhb Exp $");
 
+#include "opt_kdtrace.h"
+
 #include <sys/param.h>
 #include <sys/systm.h>
 #include <sys/bus.h>
@@ -49,10 +51,19 @@
 #include <sys/malloc.h>
 #include <sys/mutex.h>
 #include <sys/proc.h>
+#include <sys/sdt.h>
 #include <sys/sleepqueue.h>
 #include <sys/sysctl.h>
 #include <sys/smp.h>
 
+SDT_PROVIDER_DEFINE(callout_execute);
+SDT_PROBE_DEFINE(callout_execute, kernel, , callout_start);
+SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_start, 0,
+    "struct callout *");
+SDT_PROBE_DEFINE(callout_execute, kernel, , callout_end); 
+SDT_PROBE_ARGTYPE(callout_execute, kernel, , callout_end, 0,
+    "struct callout *");
+
 static int avg_depth;
 SYSCTL_INT(_debug, OID_AUTO, to_avg_depth, CTLFLAG_RD, &avg_depth, 0,
     "Average number of items examined per softclock call. Units = 1/1000");
@@ -395,7 +406,11 @@
 				binuptime(&bt1);
 #endif
 				THREAD_NO_SLEEPING();
+				SDT_PROBE(callout_execute, kernel, ,
+				    callout_start, c, 0, 0, 0, 0);
 				c_func(c_arg);
+				SDT_PROBE(callout_execute, kernel, ,
+				    callout_end, c, 0, 0, 0, 0);
 				THREAD_SLEEPING_OK();
 #ifdef DIAGNOSTIC
 				binuptime(&bt2);