Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6

[pandora-kernel.git] / lib / proportions.c

diff --git a/lib/proportions.c b/lib/proportions.c
index 9508d9a..4f387a6 100644 (file)
--- 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;
@@ -267,6 +261,38 @@ void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl)
        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);
+}
+
 /*
  * Obtain a fraction of this proportion
  *