MFcalloutng (r244355):

Make loadavg calculation callout direct. There are several reasons for it:
 - it is very simple and doesn't worth context switch to SWI;
 - since SWI is no longer used here, we can remove twelve years old hack,
excluding this SWI from from the loadavg statistics;
 - it fixes problem when eventtimer (HPET) shares interrupt with some other
device, and that interrupt thread counted as permanent loadavg of 1; now
loadavg accounted before that interrupt thread is scheduled.

Sponsored by:	Google Summer of Code 2012, iXsystems inc.
Tested by:	flo, marius, ian, Fabian Keil, markj

2 files changed, 4 insertions, 12 deletions

diff --git a/sys/kern/kern_intr.c b/sys/kern/kern_intr.c
index d2c31fd..8351ab8 100644
--- a/sys/kern/kern_intr.c
+++ b/sys/kern/kern_intr.c
@@ -1103,7 +1103,6 @@ int
 swi_add(struct intr_event **eventp, const char *name, driver_intr_t handler,
 	    void *arg, int pri, enum intr_type flags, void **cookiep)
 {
-	struct thread *td;
 	struct intr_event *ie;
 	int error;
 
@@ -1125,15 +1124,7 @@ swi_add(struct intr_event **eventp, const char *name, driver_intr_t handler,
 	}
 	error = intr_event_add_handler(ie, name, NULL, handler, arg,
 	    PI_SWI(pri), flags, cookiep);
-	if (error)
-		return (error);
-	if (pri == SWI_CLOCK) {
-		td = ie->ie_thread->it_thread;
-		thread_lock(td);
-		td->td_flags |= TDF_NOLOAD;
-		thread_unlock(td);
-	}
-	return (0);
+	return (error);
 }
 
 /*
diff --git a/sys/kern/kern_synch.c b/sys/kern/kern_synch.c
index 73dfd70..8783142 100644
--- a/sys/kern/kern_synch.c
+++ b/sys/kern/kern_synch.c
@@ -560,8 +560,9 @@ loadav(void *arg)
 	 * random variation to avoid synchronisation with processes that
 	 * run at regular intervals.
 	 */
-	callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
-	    loadav, NULL);
+	callout_reset_sbt(&loadav_callout,
+	    tick_sbt * (hz * 4 + (int)(random() % (hz * 2 + 1))), 0,
+	    loadav, NULL, C_DIRECT_EXEC | C_HARDCLOCK);
 }
 
 /* ARGSUSED */