Index: sys/sys/event.h
===================================================================
--- sys/sys/event.h	(revision 268627)
+++ sys/sys/event.h	(working copy)
@@ -133,6 +133,13 @@
 #define	NOTE_TRACKERR	0x00000002		/* could not track child */
 #define	NOTE_CHILD	0x00000004		/* am a child process */
 
+/* additional flags for EVFILE_TIMER */
+#define NOTE_SECONDS		0x00000001		/* data is seconds */
+#define NOTE_MSECONDS		0x00000002		/* data is milliseconds */
+#define NOTE_USECONDS		0x00000004		/* data is microseconds */
+#define NOTE_NSECONDS		0x00000008		/* data is nanoseconds */
+#define NOTE_PRECISION_MASK	0x0000000F		/* mask for the precision flags */
+
 struct knote;
 SLIST_HEAD(klist, knote);
 struct kqueue;
Index: sys/kern/kern_event.c
===================================================================
--- sys/kern/kern_event.c	(revision 268627)
+++ sys/kern/kern_event.c	(working copy)
@@ -524,14 +524,33 @@
  * interval timer support code.
  */
 static __inline sbintime_t
-timer2sbintime(intptr_t data)
+timer2sbintime(intptr_t data, int flags)
 {
+	sbintime_t modifier;
 
+	switch (flags & NOTE_PRECISION_MASK) {
+	case NOTE_SECONDS:
+		modifier = SBT_1S;
+		break;
+	case NOTE_MSECONDS: /* FALLTHROUGH */
+	case 0:
+		modifier = SBT_1MS;
+		break;
+	case NOTE_USECONDS:
+		modifier = SBT_1US;
+		break;
+	case NOTE_NSECONDS:
+		modifier = SBT_1NS;
+		break;
+	default:
+		return (-1);
+	}
+
 #ifdef __LP64__
-	if (data > SBT_MAX / SBT_1MS)
+	if (data > SBT_MAX / modifier)
 		return (SBT_MAX);
 #endif
-	return (SBT_1MS * data);
+	return (modifier * data);
 }
 
 static void
@@ -547,13 +566,13 @@
 	if ((kn->kn_flags & EV_ONESHOT) != EV_ONESHOT) {
 		calloutp = (struct callout *)kn->kn_hook;
 		callout_reset_sbt_on(calloutp,
-		    timer2sbintime(kn->kn_sdata), 0 /* 1ms? */,
+		    timer2sbintime(kn->kn_sdata, kn->kn_sfflags), 0,
 		    filt_timerexpire, kn, PCPU_GET(cpuid), 0);
 	}
 }
 
 /*
- * data contains amount of time to sleep, in milliseconds
+ * data contains amount of time to sleep
  */
 static int
 filt_timerattach(struct knote *kn)
@@ -566,7 +585,11 @@
 		return (EINVAL);
 	if ((intptr_t)kn->kn_sdata == 0 && (kn->kn_flags & EV_ONESHOT) == 0)
 		kn->kn_sdata = 1;
-	to = timer2sbintime(kn->kn_sdata);
+	/* Only precision unit are supported in flags so far */
+	if (kn->kn_sfflags & ~NOTE_PRECISION_MASK)
+		return (EINVAL);
+
+	to = timer2sbintime(kn->kn_sdata, kn->kn_sfflags);
 	if (to < 0)
 		return (EINVAL);
 
@@ -583,7 +606,7 @@
 	calloutp = malloc(sizeof(*calloutp), M_KQUEUE, M_WAITOK);
 	callout_init(calloutp, CALLOUT_MPSAFE);
 	kn->kn_hook = calloutp;
-	callout_reset_sbt_on(calloutp, to, 0 /* 1ms? */,
+	callout_reset_sbt_on(calloutp, to, 0,
 	    filt_timerexpire, kn, PCPU_GET(cpuid), 0);
 
 	return (0);