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-rw-r--r--lib/proportions.c37
1 files changed, 16 insertions, 21 deletions
diff --git a/lib/proportions.c b/lib/proportions.c
index 332d8c5..9508d9a 100644
--- a/lib/proportions.c
+++ b/lib/proportions.c
@@ -190,6 +190,8 @@ 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);
@@ -230,31 +232,24 @@ 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);
}
@@ -267,7 +262,7 @@ 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);
+ __percpu_counter_add(&pl->events, 1, PROP_BATCH);
percpu_counter_add(&pg->events, 1);
prop_put_global(pd, pg);
}
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