X-Git-Url: http://ftp.safe.ca/?a=blobdiff_plain;f=lib%2Fproportions.c;h=d50746a79de2a846187137a2ffb11993c23127e8;hb=c91d3376e5f4277173a22f0ef9989125c318bacb;hp=332d8c58184d4964406dfe71179b877fd9f927f6;hpb=145ca25eb2fbd20d4faf1bad4628c7650332058f;p=safe%2Fjmp%2Flinux-2.6

diff --git a/lib/proportions.c b/lib/proportions.c
index 332d8c5..d50746a 100644
--- a/lib/proportions.c
+++ b/lib/proportions.c
@@ -73,12 +73,6 @@
 #include <linux/proportions.h>
 #include <linux/rcupdate.h>
 
-/*
- * Limit the time part in order to ensure there are some bits left for the
- * cycle counter.
- */
-#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4)
-
 int prop_descriptor_init(struct prop_descriptor *pd, int shift)
 {
 	int err;
@@ -89,11 +83,11 @@ int prop_descriptor_init(struct prop_descriptor *pd, int shift)
 	pd->index = 0;
 	pd->pg[0].shift = shift;
 	mutex_init(&pd->mutex);
-	err = percpu_counter_init_irq(&pd->pg[0].events, 0);
+	err = percpu_counter_init(&pd->pg[0].events, 0);
 	if (err)
 		goto out;
 
-	err = percpu_counter_init_irq(&pd->pg[1].events, 0);
+	err = percpu_counter_init(&pd->pg[1].events, 0);
 	if (err)
 		percpu_counter_destroy(&pd->pg[0].events);
 
@@ -153,6 +147,7 @@ out:
  * this is used to track the active references.
  */
 static struct prop_global *prop_get_global(struct prop_descriptor *pd)
+__acquires(RCU)
 {
 	int index;
 
@@ -166,6 +161,7 @@ static struct prop_global *prop_get_global(struct prop_descriptor *pd)
 }
 
 static void prop_put_global(struct prop_descriptor *pd, struct prop_global *pg)
+__releases(RCU)
 {
 	rcu_read_unlock();
 }
@@ -190,12 +186,14 @@ prop_adjust_shift(int *pl_shift, unsigned long *pl_period, int new_shift)
  * PERCPU
  */
 
+#define PROP_BATCH (8*(1+ilog2(nr_cpu_ids)))
+
 int prop_local_init_percpu(struct prop_local_percpu *pl)
 {
 	spin_lock_init(&pl->lock);
 	pl->shift = 0;
 	pl->period = 0;
-	return percpu_counter_init_irq(&pl->events, 0);
+	return percpu_counter_init(&pl->events, 0);
 }
 
 void prop_local_destroy_percpu(struct prop_local_percpu *pl)
@@ -230,31 +228,24 @@ void prop_norm_percpu(struct prop_global *pg, struct prop_local_percpu *pl)
 
 	spin_lock_irqsave(&pl->lock, flags);
 	prop_adjust_shift(&pl->shift, &pl->period, pg->shift);
+
 	/*
 	 * For each missed period, we half the local counter.
 	 * basically:
 	 *   pl->events >> (global_period - pl->period);
-	 *
-	 * but since the distributed nature of percpu counters make division
-	 * rather hard, use a regular subtraction loop. This is safe, because
-	 * the events will only every be incremented, hence the subtraction
-	 * can never result in a negative number.
 	 */
-	while (pl->period != global_period) {
-		unsigned long val = percpu_counter_read(&pl->events);
-		unsigned long half = (val + 1) >> 1;
-
-		/*
-		 * Half of zero won't be much less, break out.
-		 * This limits the loop to shift iterations, even
-		 * if we missed a million.
-		 */
-		if (!val)
-			break;
-
-		percpu_counter_add(&pl->events, -half);
-		pl->period += period;
-	}
+	period = (global_period - pl->period) >> (pg->shift - 1);
+	if (period < BITS_PER_LONG) {
+		s64 val = percpu_counter_read(&pl->events);
+
+		if (val < (nr_cpu_ids * PROP_BATCH))
+			val = percpu_counter_sum(&pl->events);
+
+		__percpu_counter_add(&pl->events, -val + (val >> period),
+					PROP_BATCH);
+	} else
+		percpu_counter_set(&pl->events, 0);
+
 	pl->period = global_period;
 	spin_unlock_irqrestore(&pl->lock, flags);
 }
@@ -267,8 +258,40 @@ void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl)
 	struct prop_global *pg = prop_get_global(pd);
 
 	prop_norm_percpu(pg, pl);
+	__percpu_counter_add(&pl->events, 1, PROP_BATCH);
+	percpu_counter_add(&pg->events, 1);
+	prop_put_global(pd, pg);
+}
+
+/*
+ * identical to __prop_inc_percpu, except that it limits this pl's fraction to
+ * @frac/PROP_FRAC_BASE by ignoring events when this limit has been exceeded.
+ */
+void __prop_inc_percpu_max(struct prop_descriptor *pd,
+			   struct prop_local_percpu *pl, long frac)
+{
+	struct prop_global *pg = prop_get_global(pd);
+
+	prop_norm_percpu(pg, pl);
+
+	if (unlikely(frac != PROP_FRAC_BASE)) {
+		unsigned long period_2 = 1UL << (pg->shift - 1);
+		unsigned long counter_mask = period_2 - 1;
+		unsigned long global_count;
+		long numerator, denominator;
+
+		numerator = percpu_counter_read_positive(&pl->events);
+		global_count = percpu_counter_read(&pg->events);
+		denominator = period_2 + (global_count & counter_mask);
+
+		if (numerator > ((denominator * frac) >> PROP_FRAC_SHIFT))
+			goto out_put;
+	}
+
 	percpu_counter_add(&pl->events, 1);
 	percpu_counter_add(&pg->events, 1);
+
+out_put:
 	prop_put_global(pd, pg);
 }