diff options
| -rw-r--r-- | lib/proportions.c | 37 |
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); } |
