diff options
| -rw-r--r-- | kernel/sched_fair.c | 76 |
1 files changed, 43 insertions, 33 deletions
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c index ff7692ccda89..3e1fd96c6cf9 100644 --- a/kernel/sched_fair.c +++ b/kernel/sched_fair.c @@ -2097,6 +2097,7 @@ struct sd_lb_stats { unsigned long max_load; unsigned long busiest_load_per_task; unsigned long busiest_nr_running; + unsigned long busiest_group_capacity; int group_imb; /* Is there imbalance in this sd */ #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) @@ -2416,14 +2417,12 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, unsigned long load, max_cpu_load, min_cpu_load; int i; unsigned int balance_cpu = -1, first_idle_cpu = 0; - unsigned long sum_avg_load_per_task; - unsigned long avg_load_per_task; + unsigned long avg_load_per_task = 0; if (local_group) balance_cpu = group_first_cpu(group); /* Tally up the load of all CPUs in the group */ - sum_avg_load_per_task = avg_load_per_task = 0; max_cpu_load = 0; min_cpu_load = ~0UL; @@ -2453,7 +2452,6 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, sgs->sum_nr_running += rq->nr_running; sgs->sum_weighted_load += weighted_cpuload(i); - sum_avg_load_per_task += cpu_avg_load_per_task(i); } /* @@ -2473,7 +2471,6 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, /* Adjust by relative CPU power of the group */ sgs->avg_load = (sgs->group_load * SCHED_LOAD_SCALE) / group->cpu_power; - /* * Consider the group unbalanced when the imbalance is larger * than the average weight of two tasks. @@ -2483,8 +2480,8 @@ static inline void update_sg_lb_stats(struct sched_domain *sd, * normalized nr_running number somewhere that negates * the hierarchy? */ - avg_load_per_task = (sum_avg_load_per_task * SCHED_LOAD_SCALE) / - group->cpu_power; + if (sgs->sum_nr_running) + avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; if ((max_cpu_load - min_cpu_load) > 2*avg_load_per_task) sgs->group_imb = 1; @@ -2553,6 +2550,7 @@ static inline void update_sd_lb_stats(struct sched_domain *sd, int this_cpu, sds->max_load = sgs.avg_load; sds->busiest = group; sds->busiest_nr_running = sgs.sum_nr_running; + sds->busiest_group_capacity = sgs.group_capacity; sds->busiest_load_per_task = sgs.sum_weighted_load; sds->group_imb = sgs.group_imb; } @@ -2575,6 +2573,7 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, { unsigned long tmp, pwr_now = 0, pwr_move = 0; unsigned int imbn = 2; + unsigned long scaled_busy_load_per_task; if (sds->this_nr_running) { sds->this_load_per_task /= sds->this_nr_running; @@ -2585,8 +2584,12 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, sds->this_load_per_task = cpu_avg_load_per_task(this_cpu); - if (sds->max_load - sds->this_load + sds->busiest_load_per_task >= - sds->busiest_load_per_task * imbn) { + scaled_busy_load_per_task = sds->busiest_load_per_task + * SCHED_LOAD_SCALE; + scaled_busy_load_per_task /= sds->busiest->cpu_power; + + if (sds->max_load - sds->this_load + scaled_busy_load_per_task >= + (scaled_busy_load_per_task * imbn)) { *imbalance = sds->busiest_load_per_task; return; } @@ -2637,7 +2640,14 @@ static inline void fix_small_imbalance(struct sd_lb_stats *sds, static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, unsigned long *imbalance) { - unsigned long max_pull; + unsigned long max_pull, load_above_capacity = ~0UL; + + sds->busiest_load_per_task /= sds->busiest_nr_running; + if (sds->group_imb) { + sds->busiest_load_per_task = + min(sds->busiest_load_per_task, sds->avg_load); + } + /* * In the presence of smp nice balancing, certain scenarios can have * max load less than avg load(as we skip the groups at or below @@ -2648,9 +2658,29 @@ static inline void calculate_imbalance(struct sd_lb_stats *sds, int this_cpu, return fix_small_imbalance(sds, this_cpu, imbalance); } - /* Don't want to pull so many tasks that a group would go idle */ - max_pull = min(sds->max_load - sds->avg_load, - sds->max_load - sds->busiest_load_per_task); + if (!sds->group_imb) { + /* + * Don't want to pull so many tasks that a group would go idle. + */ + load_above_capacity = (sds->busiest_nr_running - + sds->busiest_group_capacity); + + load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_LOAD_SCALE); + + load_above_capacity /= sds->busiest->cpu_power; + } + + /* + * We're trying to get all the cpus to the average_load, so we don't + * want to push ourselves above the average load, nor do we wish to + * reduce the max loaded cpu below the average load. At the same time, + * we also don't want to reduce the group load below the group capacity + * (so that we can implement power-savings policies etc). Thus we look + * for the minimum possible imbalance. + * Be careful of negative numbers as they'll appear as very large values + * with unsigned longs. + */ + max_pull = min(sds->max_load - sds->avg_load, load_above_capacity); /* How much load to actually move to equalise the imbalance */ *imbalance = min(max_pull * sds->busiest->cpu_power, @@ -2718,7 +2748,6 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, * 4) This group is more busy than the avg busieness at this * sched_domain. * 5) The imbalance is within the specified limit. - * 6) Any rebalance would lead to ping-pong */ if (!(*balance)) goto ret; @@ -2737,25 +2766,6 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, if (100 * sds.max_load <= sd->imbalance_pct * sds.this_load) goto out_balanced; - sds.busiest_load_per_task /= sds.busiest_nr_running; - if (sds.group_imb) - sds.busiest_load_per_task = - min(sds.busiest_load_per_task, sds.avg_load); - - /* - * We're trying to get all the cpus to the average_load, so we don't - * want to push ourselves above the average load, nor do we wish to - * reduce the max loaded cpu below the average load, as either of these - * actions would just result in more rebalancing later, and ping-pong - * tasks around. Thus we look for the minimum possible imbalance. - * Negative imbalances (*we* are more loaded than anyone else) will - * be counted as no imbalance for these purposes -- we can't fix that - * by pulling tasks to us. Be careful of negative numbers as they'll - * appear as very large values with unsigned longs. - */ - if (sds.max_load <= sds.busiest_load_per_task) - goto out_balanced; - /* Looks like there is an imbalance. Compute it */ calculate_imbalance(&sds, this_cpu, imbalance); return sds.busiest; |
