diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched.c | 131 |
1 files changed, 70 insertions, 61 deletions
diff --git a/kernel/sched.c b/kernel/sched.c index ec715f97202..540147e5e82 100644 --- a/kernel/sched.c +++ b/kernel/sched.c @@ -3484,6 +3484,71 @@ group_next: } while (group != sd->groups); } + +/** + * fix_small_imbalance - Calculate the minor imbalance that exists + * amongst the groups of a sched_domain, during + * load balancing. + * @sds: Statistics of the sched_domain whose imbalance is to be calculated. + * @this_cpu: The cpu at whose sched_domain we're performing load-balance. + * @imbalance: Variable to store the imbalance. + */ +static inline void fix_small_imbalance(struct sd_lb_stats *sds, + int this_cpu, unsigned long *imbalance) +{ + unsigned long tmp, pwr_now = 0, pwr_move = 0; + unsigned int imbn = 2; + + if (sds->this_nr_running) { + sds->this_load_per_task /= sds->this_nr_running; + if (sds->busiest_load_per_task > + sds->this_load_per_task) + imbn = 1; + } else + 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) { + *imbalance = sds->busiest_load_per_task; + return; + } + + /* + * OK, we don't have enough imbalance to justify moving tasks, + * however we may be able to increase total CPU power used by + * moving them. + */ + + pwr_now += sds->busiest->__cpu_power * + min(sds->busiest_load_per_task, sds->max_load); + pwr_now += sds->this->__cpu_power * + min(sds->this_load_per_task, sds->this_load); + pwr_now /= SCHED_LOAD_SCALE; + + /* Amount of load we'd subtract */ + tmp = sg_div_cpu_power(sds->busiest, + sds->busiest_load_per_task * SCHED_LOAD_SCALE); + if (sds->max_load > tmp) + pwr_move += sds->busiest->__cpu_power * + min(sds->busiest_load_per_task, sds->max_load - tmp); + + /* Amount of load we'd add */ + if (sds->max_load * sds->busiest->__cpu_power < + sds->busiest_load_per_task * SCHED_LOAD_SCALE) + tmp = sg_div_cpu_power(sds->this, + sds->max_load * sds->busiest->__cpu_power); + else + tmp = sg_div_cpu_power(sds->this, + sds->busiest_load_per_task * SCHED_LOAD_SCALE); + pwr_move += sds->this->__cpu_power * + min(sds->this_load_per_task, sds->this_load + tmp); + pwr_move /= SCHED_LOAD_SCALE; + + /* Move if we gain throughput */ + if (pwr_move > pwr_now) + *imbalance = sds->busiest_load_per_task; +} /******* find_busiest_group() helpers end here *********************/ /* @@ -3547,7 +3612,8 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, */ if (sds.max_load < sds.avg_load) { *imbalance = 0; - goto small_imbalance; + fix_small_imbalance(&sds, this_cpu, imbalance); + goto ret_busiest; } /* Don't want to pull so many tasks that a group would go idle */ @@ -3565,67 +3631,10 @@ find_busiest_group(struct sched_domain *sd, int this_cpu, * a think about bumping its value to force at least one task to be * moved */ - if (*imbalance < sds.busiest_load_per_task) { - unsigned long tmp, pwr_now, pwr_move; - unsigned int imbn; - -small_imbalance: - pwr_move = pwr_now = 0; - imbn = 2; - if (sds.this_nr_running) { - sds.this_load_per_task /= sds.this_nr_running; - if (sds.busiest_load_per_task > - sds.this_load_per_task) - imbn = 1; - } else - 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) { - *imbalance = sds.busiest_load_per_task; - return sds.busiest; - } - - /* - * OK, we don't have enough imbalance to justify moving tasks, - * however we may be able to increase total CPU power used by - * moving them. - */ - - pwr_now += sds.busiest->__cpu_power * - min(sds.busiest_load_per_task, sds.max_load); - pwr_now += sds.this->__cpu_power * - min(sds.this_load_per_task, sds.this_load); - pwr_now /= SCHED_LOAD_SCALE; - - /* Amount of load we'd subtract */ - tmp = sg_div_cpu_power(sds.busiest, - sds.busiest_load_per_task * SCHED_LOAD_SCALE); - if (sds.max_load > tmp) - pwr_move += sds.busiest->__cpu_power * - min(sds.busiest_load_per_task, - sds.max_load - tmp); - - /* Amount of load we'd add */ - if (sds.max_load * sds.busiest->__cpu_power < - sds.busiest_load_per_task * SCHED_LOAD_SCALE) - tmp = sg_div_cpu_power(sds.this, - sds.max_load * sds.busiest->__cpu_power); - else - tmp = sg_div_cpu_power(sds.this, - sds.busiest_load_per_task * SCHED_LOAD_SCALE); - pwr_move += sds.this->__cpu_power * - min(sds.this_load_per_task, - sds.this_load + tmp); - pwr_move /= SCHED_LOAD_SCALE; - - /* Move if we gain throughput */ - if (pwr_move > pwr_now) - *imbalance = sds.busiest_load_per_task; - } + if (*imbalance < sds.busiest_load_per_task) + fix_small_imbalance(&sds, this_cpu, imbalance); +ret_busiest: return sds.busiest; out_balanced: |