Store an absolute tick value in callout entries so that a subtraction on

hash chain traversal isn't needed.  This also allows untimeout to recompute
the hash to find the bucket that the entry to remove is stored in so
that each callout entry no longer needs to store that information.

Reviewed by:	 Nate Williams <nate@mt.sri.com>

1 files changed, 18 insertions, 10 deletions

diff --git a/sys/kern/kern_timeout.c b/sys/kern/kern_timeout.c
index b14c552..f1b30b5 100644
--- a/sys/kern/kern_timeout.c
+++ b/sys/kern/kern_timeout.c
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	@(#)kern_clock.c	8.5 (Berkeley) 1/21/94
- * $Id: kern_clock.c,v 1.40 1997/09/07 05:25:43 bde Exp $
+ * $Id: kern_clock.c,v 1.41 1997/09/21 22:00:07 gibbs Exp $
  */
 
 /* Portions of this software are covered by the following: */
@@ -696,7 +696,9 @@ void
 softclock()
 {
 	register struct callout *c;
+	register struct callout_tailq *bucket;
 	register int s;
+	register int curticks;
 	register int steps;	/*
 				 * Number of steps taken since
 				 * we last allowed interrupts.
@@ -709,16 +711,22 @@ softclock()
 	steps = 0;
 	s = splhigh();
 	while (softticks != ticks) {
-		c = TAILQ_FIRST(&callwheel[++softticks & callwheelmask]);
+		softticks++;
+		/*
+		 * softticks may be modified by hard clock, so cache
+		 * it while we work on a given bucket.
+		 */
+		curticks = softticks;
+		bucket = &callwheel[curticks & callwheelmask];
+		c = TAILQ_FIRST(bucket);
 		while (c) {
-			if (c->c_time > 0) {
-				c->c_time--;
+			if (c->c_time != curticks) {
 				c = TAILQ_NEXT(c, c_links.tqe);
 				++steps;
 				if (steps >= MAX_SOFTCLOCK_STEPS) {
 					nextsoftcheck = c;
+					/* Give interrupts a chance. */
 					splx(s);
-					/* Give hardclock() a chance. */
 					s = splhigh();
 					c = nextsoftcheck;
 					steps = 0;
@@ -728,7 +736,7 @@ softclock()
 				void *c_arg;
 
 				nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
-				TAILQ_REMOVE(c->c_bucket, c, c_links.tqe);
+				TAILQ_REMOVE(bucket, c, c_links.tqe);
 				c_func = c->c_func;
 				c_arg = c->c_arg;
 				c->c_func = NULL;
@@ -786,9 +794,9 @@ timeout(ftn, arg, to_ticks)
 	SLIST_REMOVE_HEAD(&callfree, c_links.sle);
 	new->c_arg = arg;
 	new->c_func = ftn;
-	new->c_time = to_ticks >> callwheelbits;
-	new->c_bucket = &callwheel[(ticks + to_ticks) & callwheelmask];
-	TAILQ_INSERT_TAIL(new->c_bucket, new, c_links.tqe);
+	new->c_time = ticks + to_ticks;
+	TAILQ_INSERT_TAIL(&callwheel[new->c_time & callwheelmask],
+			  new, c_links.tqe);
 
 	splx(s);
 	handle.callout = new;
@@ -818,7 +826,7 @@ untimeout(ftn, arg, handle)
 		if (nextsoftcheck == handle.callout) {
 			nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe);
 		}
-		TAILQ_REMOVE(handle.callout->c_bucket,
+		TAILQ_REMOVE(&callwheel[handle.callout->c_time & callwheelmask],
 			     handle.callout, c_links.tqe);
 		handle.callout->c_func = NULL;
 		SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle);