diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/core.c | 17 | ||||
| -rw-r--r-- | kernel/sched/cputime.c | 2 | ||||
| -rw-r--r-- | kernel/sched/fair.c | 511 | ||||
| -rw-r--r-- | kernel/smp.c | 14 |
4 files changed, 303 insertions, 241 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 57c186d..b8e2162 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -2677,7 +2677,7 @@ void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, if (unlikely(!q)) return; - if (unlikely(!nr_exclusive)) + if (unlikely(nr_exclusive != 1)) wake_flags = 0; spin_lock_irqsave(&q->lock, flags); @@ -4964,7 +4964,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent) SD_BALANCE_FORK | SD_BALANCE_EXEC | SD_SHARE_CPUPOWER | - SD_SHARE_PKG_RESOURCES); + SD_SHARE_PKG_RESOURCES | + SD_PREFER_SIBLING); if (nr_node_ids == 1) pflags &= ~SD_SERIALIZE; } @@ -5173,6 +5174,13 @@ cpu_attach_domain(struct sched_domain *sd, struct root_domain *rd, int cpu) tmp->parent = parent->parent; if (parent->parent) parent->parent->child = tmp; + /* + * Transfer SD_PREFER_SIBLING down in case of a + * degenerate parent; the spans match for this + * so the property transfers. + */ + if (parent->flags & SD_PREFER_SIBLING) + tmp->flags |= SD_PREFER_SIBLING; destroy_sched_domain(parent, cpu); } else tmp = tmp->parent; @@ -6239,8 +6247,9 @@ match1: ; } + n = ndoms_cur; if (doms_new == NULL) { - ndoms_cur = 0; + n = 0; doms_new = &fallback_doms; cpumask_andnot(doms_new[0], cpu_active_mask, cpu_isolated_map); WARN_ON_ONCE(dattr_new); @@ -6248,7 +6257,7 @@ match1: /* Build new domains */ for (i = 0; i < ndoms_new; i++) { - for (j = 0; j < ndoms_cur && !new_topology; j++) { + for (j = 0; j < n && !new_topology; j++) { if (cpumask_equal(doms_new[i], doms_cur[j]) && dattrs_equal(dattr_new, i, dattr_cur, j)) goto match2; diff --git a/kernel/sched/cputime.c b/kernel/sched/cputime.c index a7959e0..e89ccef 100644 --- a/kernel/sched/cputime.c +++ b/kernel/sched/cputime.c @@ -121,7 +121,7 @@ static inline void task_group_account_field(struct task_struct *p, int index, * is the only cgroup, then nothing else should be necessary. * */ - __get_cpu_var(kernel_cpustat).cpustat[index] += tmp; + __this_cpu_add(kernel_cpustat.cpustat[index], tmp); cpuacct_account_field(p, index, tmp); } diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 8977a24..7f0a5e6 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4277,50 +4277,56 @@ static unsigned long task_h_load(struct task_struct *p) /********** Helpers for find_busiest_group ************************/ /* - * sd_lb_stats - Structure to store the statistics of a sched_domain - * during load balancing. - */ -struct sd_lb_stats { - struct sched_group *busiest; /* Busiest group in this sd */ - struct sched_group *this; /* Local group in this sd */ - unsigned long total_load; /* Total load of all groups in sd */ - unsigned long total_pwr; /* Total power of all groups in sd */ - unsigned long avg_load; /* Average load across all groups in sd */ - - /** Statistics of this group */ - unsigned long this_load; - unsigned long this_load_per_task; - unsigned long this_nr_running; - unsigned long this_has_capacity; - unsigned int this_idle_cpus; - - /* Statistics of the busiest group */ - unsigned int busiest_idle_cpus; - unsigned long max_load; - unsigned long busiest_load_per_task; - unsigned long busiest_nr_running; - unsigned long busiest_group_capacity; - unsigned long busiest_has_capacity; - unsigned int busiest_group_weight; - - int group_imb; /* Is there imbalance in this sd */ -}; - -/* * sg_lb_stats - stats of a sched_group required for load_balancing */ struct sg_lb_stats { unsigned long avg_load; /*Avg load across the CPUs of the group */ unsigned long group_load; /* Total load over the CPUs of the group */ - unsigned long sum_nr_running; /* Nr tasks running in the group */ unsigned long sum_weighted_load; /* Weighted load of group's tasks */ - unsigned long group_capacity; - unsigned long idle_cpus; - unsigned long group_weight; + unsigned long load_per_task; + unsigned long group_power; + unsigned int sum_nr_running; /* Nr tasks running in the group */ + unsigned int group_capacity; + unsigned int idle_cpus; + unsigned int group_weight; int group_imb; /* Is there an imbalance in the group ? */ int group_has_capacity; /* Is there extra capacity in the group? */ }; +/* + * sd_lb_stats - Structure to store the statistics of a sched_domain + * during load balancing. + */ +struct sd_lb_stats { + struct sched_group *busiest; /* Busiest group in this sd */ + struct sched_group *local; /* Local group in this sd */ + unsigned long total_load; /* Total load of all groups in sd */ + unsigned long total_pwr; /* Total power of all groups in sd */ + unsigned long avg_load; /* Average load across all groups in sd */ + + struct sg_lb_stats busiest_stat;/* Statistics of the busiest group */ + struct sg_lb_stats local_stat; /* Statistics of the local group */ +}; + +static inline void init_sd_lb_stats(struct sd_lb_stats *sds) +{ + /* + * Skimp on the clearing to avoid duplicate work. We can avoid clearing + * local_stat because update_sg_lb_stats() does a full clear/assignment. + * We must however clear busiest_stat::avg_load because + * update_sd_pick_busiest() reads this before assignment. + */ + *sds = (struct sd_lb_stats){ + .busiest = NULL, + .local = NULL, + .total_load = 0UL, + .total_pwr = 0UL, + .busiest_stat = { + .avg_load = 0UL, + }, + }; +} + /** * get_sd_load_idx - Obtain the load index for a given sched domain. * @sd: The sched_domain whose load_idx is to be obtained. @@ -4504,33 +4510,99 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group) return 0; } +/* + * Group imbalance indicates (and tries to solve) the problem where balancing + * groups is inadequate due to tsk_cpus_allowed() constraints. + * + * Imagine a situation of two groups of 4 cpus each and 4 tasks each with a + * cpumask covering 1 cpu of the first group and 3 cpus of the second group. + * Something like: + * + * { 0 1 2 3 } { 4 5 6 7 } + * * * * * + * + * If we were to balance group-wise we'd place two tasks in the first group and + * two tasks in the second group. Clearly this is undesired as it will overload + * cpu 3 and leave one of the cpus in the second group unused. + * + * The current solution to this issue is detecting the skew in the first group + * by noticing it has a cpu that is overloaded while the remaining cpus are + * idle -- or rather, there's a distinct imbalance in the cpus; see + * sg_imbalanced(). + * + * When this is so detected; this group becomes a candidate for busiest; see + * update_sd_pick_busiest(). And calculcate_imbalance() and + * find_busiest_group() avoid some of the usual balance conditional to allow it + * to create an effective group imbalance. + * + * This is a somewhat tricky proposition since the next run might not find the + * group imbalance and decide the groups need to be balanced again. A most + * subtle and fragile situation. + */ + +struct sg_imb_stats { + unsigned long max_nr_running, min_nr_running; + unsigned long max_cpu_load, min_cpu_load; +}; + +static inline void init_sg_imb_stats(struct sg_imb_stats *sgi) +{ + sgi->max_cpu_load = sgi->max_nr_running = 0UL; + sgi->min_cpu_load = sgi->min_nr_running = ~0UL; +} + +static inline void +update_sg_imb_stats(struct sg_imb_stats *sgi, + unsigned long load, unsigned long nr_running) +{ + if (load > sgi->max_cpu_load) + sgi->max_cpu_load = load; + if (sgi->min_cpu_load > load) + sgi->min_cpu_load = load; + + if (nr_running > sgi->max_nr_running) + sgi->max_nr_running = nr_running; + if (sgi->min_nr_running > nr_running) + sgi->min_nr_running = nr_running; +} + +static inline int +sg_imbalanced(struct sg_lb_stats *sgs, struct sg_imb_stats *sgi) +{ + /* + * Consider the group unbalanced when the imbalance is larger + * than the average weight of a task. + * + * APZ: with cgroup the avg task weight can vary wildly and + * might not be a suitable number - should we keep a + * normalized nr_running number somewhere that negates + * the hierarchy? + */ + if ((sgi->max_cpu_load - sgi->min_cpu_load) >= sgs->load_per_task && + (sgi->max_nr_running - sgi->min_nr_running) > 1) + return 1; + + return 0; +} + /** * update_sg_lb_stats - Update sched_group's statistics for load balancing. * @env: The load balancing environment. * @group: sched_group whose statistics are to be updated. * @load_idx: Load index of sched_domain of this_cpu for load calc. * @local_group: Does group contain this_cpu. - * @balance: Should we balance. * @sgs: variable to hold the statistics for this group. */ static inline void update_sg_lb_stats(struct lb_env *env, struct sched_group *group, int load_idx, - int local_group, int *balance, struct sg_lb_stats *sgs) + int local_group, struct sg_lb_stats *sgs) { - unsigned long nr_running, max_nr_running, min_nr_running; - unsigned long load, max_cpu_load, min_cpu_load; - unsigned int balance_cpu = -1, first_idle_cpu = 0; - unsigned long avg_load_per_task = 0; + struct sg_imb_stats sgi; + unsigned long nr_running; + unsigned long load; int i; - if (local_group) - balance_cpu = group_balance_cpu(group); - - /* Tally up the load of all CPUs in the group */ - max_cpu_load = 0; - min_cpu_load = ~0UL; - max_nr_running = 0; - min_nr_running = ~0UL; + init_sg_imb_stats(&sgi); for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { struct rq *rq = cpu_rq(i); @@ -4539,24 +4611,10 @@ static inline void update_sg_lb_stats(struct lb_env *env, /* Bias balancing toward cpus of our domain */ if (local_group) { - if (idle_cpu(i) && !first_idle_cpu && - cpumask_test_cpu(i, sched_group_mask(group))) { - first_idle_cpu = 1; - balance_cpu = i; - } - load = target_load(i, load_idx); } else { load = source_load(i, load_idx); - if (load > max_cpu_load) - max_cpu_load = load; - if (min_cpu_load > load) - min_cpu_load = load; - - if (nr_running > max_nr_running) - max_nr_running = nr_running; - if (min_nr_running > nr_running) - min_nr_running = nr_running; + update_sg_imb_stats(&sgi, load, nr_running); } sgs->group_load += load; @@ -4566,46 +4624,25 @@ static inline void update_sg_lb_stats(struct lb_env *env, sgs->idle_cpus++; } - /* - * First idle cpu or the first cpu(busiest) in this sched group - * is eligible for doing load balancing at this and above - * domains. In the newly idle case, we will allow all the cpu's - * to do the newly idle load balance. - */ - if (local_group) { - if (env->idle != CPU_NEWLY_IDLE) { - if (balance_cpu != env->dst_cpu) { - *balance = 0; - return; - } - update_group_power(env->sd, env->dst_cpu); - } else if (time_after_eq(jiffies, group->sgp->next_update)) - update_group_power(env->sd, env->dst_cpu); - } + if (local_group && (env->idle != CPU_NEWLY_IDLE || + time_after_eq(jiffies, group->sgp->next_update))) + update_group_power(env->sd, env->dst_cpu); /* Adjust by relative CPU power of the group */ - sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power; + sgs->group_power = group->sgp->power; + sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_power; - /* - * Consider the group unbalanced when the imbalance is larger - * than the average weight of a task. - * - * APZ: with cgroup the avg task weight can vary wildly and - * might not be a suitable number - should we keep a - * normalized nr_running number somewhere that negates - * the hierarchy? - */ if (sgs->sum_nr_running) - avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; + sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running; - if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && - (max_nr_running - min_nr_running) > 1) - sgs->group_imb = 1; + sgs->group_imb = sg_imbalanced(sgs, &sgi); + + sgs->group_capacity = + DIV_ROUND_CLOSEST(sgs->group_power, SCHED_POWER_SCALE); - sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power, - SCHED_POWER_SCALE); if (!sgs->group_capacity) sgs->group_capacity = fix_small_capacity(env->sd, group); + sgs->group_weight = group->group_weight; if (sgs->group_capacity > sgs->sum_nr_running) @@ -4630,7 +4667,7 @@ static bool update_sd_pick_busiest(struct lb_env *env, struct sched_group *sg, struct sg_lb_stats *sgs) { - if (sgs->avg_load <= sds->max_load) + if (sgs->avg_load <= sds->busiest_stat.avg_load) return false; if (sgs->sum_nr_running > sgs->group_capacity) @@ -4663,11 +4700,11 @@ static bool update_sd_pick_busiest(struct lb_env *env, * @sds: variable to hold the statistics for this sched_domain. */ static inline void update_sd_lb_stats(struct lb_env *env, - int *balance, struct sd_lb_stats *sds) + struct sd_lb_stats *sds) { struct sched_domain *child = env->sd->child; struct sched_group *sg = env->sd->groups; - struct sg_lb_stats sgs; + struct sg_lb_stats tmp_sgs; int load_idx, prefer_sibling = 0; if (child && child->flags & SD_PREFER_SIBLING) @@ -4676,17 +4713,17 @@ static inline void update_sd_lb_stats(struct lb_env *env, load_idx = get_sd_load_idx(env->sd, env->idle); do { + struct sg_lb_stats *sgs = &tmp_sgs; int local_group; local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg)); - memset(&sgs, 0, sizeof(sgs)); - update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs); - - if (local_group && !(*balance)) - return; + if (local_group) { + sds->local = sg; + sgs = &sds->local_stat; + } - sds->total_load += sgs.group_load; - sds->total_pwr += sg->sgp->power; + memset(sgs, 0, sizeof(*sgs)); + update_sg_lb_stats(env, sg, load_idx, local_group, sgs); /* * In case the child domain prefers tasks go to siblings @@ -4698,26 +4735,17 @@ static inline void update_sd_lb_stats(struct lb_env *env, * heaviest group when it is already under-utilized (possible * with a large weight task outweighs the tasks on the system). */ - if (prefer_sibling && !local_group && sds->this_has_capacity) - sgs.group_capacity = min(sgs.group_capacity, 1UL); + if (prefer_sibling && !local_group && + sds->local && sds->local_stat.group_has_capacity) + sgs->group_capacity = min(sgs->group_capacity, 1U); - if (local_group) { - sds->this_load = sgs.avg_load; - sds->this = sg; - sds->this_nr_running = sgs.sum_nr_running; - sds->this_load_per_task = sgs.sum_weighted_load; - sds->this_has_capacity = sgs.group_has_capacity; - sds->this_idle_cpus = sgs.idle_cpus; - } else if (update_sd_pick_busiest(env, sds, sg, &sgs)) { - sds->max_load = sgs.avg_load; + /* Now, start updating sd_lb_stats */ + sds->total_load += sgs->group_load; + sds->total_pwr += sgs->group_power; + + if (!local_group && update_sd_pick_busiest(env, sds, sg, sgs)) { sds->busiest = sg; - sds->busiest_nr_running = sgs.sum_nr_running; - sds->busiest_idle_cpus = sgs.idle_cpus; - sds->busiest_group_capacity = sgs.group_capacity; - sds->busiest_load_per_task = sgs.sum_weighted_load; - sds->busiest_has_capacity = sgs.group_has_capacity; - sds->busiest_group_weight = sgs.group_weight; - sds->group_imb = sgs.group_imb; + sds->busiest_stat = *sgs; } sg = sg->next; @@ -4762,7 +4790,8 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds) return 0; env->imbalance = DIV_ROUND_CLOSEST( - sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE); + sds->busiest_stat.avg_load * sds->busiest_stat.group_power, + SCHED_POWER_SCALE); return 1; } @@ -4780,24 +4809,23 @@ void fix_small_imbalance(struct lb_env *env, 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; + struct sg_lb_stats *local, *busiest; - 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(env->dst_cpu); - } + local = &sds->local_stat; + busiest = &sds->busiest_stat; - scaled_busy_load_per_task = sds->busiest_load_per_task - * SCHED_POWER_SCALE; - scaled_busy_load_per_task /= sds->busiest->sgp->power; + if (!local->sum_nr_running) + local->load_per_task = cpu_avg_load_per_task(env->dst_cpu); + else if (busiest->load_per_task > local->load_per_task) + imbn = 1; - if (sds->max_load - sds->this_load + scaled_busy_load_per_task >= - (scaled_busy_load_per_task * imbn)) { - env->imbalance = sds->busiest_load_per_task; + scaled_busy_load_per_task = + (busiest->load_per_task * SCHED_POWER_SCALE) / + busiest->group_power; + + if (busiest->avg_load - local->avg_load + scaled_busy_load_per_task >= + (scaled_busy_load_per_task * imbn)) { + env->imbalance = busiest->load_per_task; return; } @@ -4807,34 +4835,37 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) * moving them. */ - pwr_now += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load); - pwr_now += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load); + pwr_now += busiest->group_power * + min(busiest->load_per_task, busiest->avg_load); + pwr_now += local->group_power * + min(local->load_per_task, local->avg_load); pwr_now /= SCHED_POWER_SCALE; /* Amount of load we'd subtract */ - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->busiest->sgp->power; - if (sds->max_load > tmp) - pwr_move += sds->busiest->sgp->power * - min(sds->busiest_load_per_task, sds->max_load - tmp); + tmp = (busiest->load_per_task * SCHED_POWER_SCALE) / + busiest->group_power; + if (busiest->avg_load > tmp) { + pwr_move += busiest->group_power * + min(busiest->load_per_task, + busiest->avg_load - tmp); + } /* Amount of load we'd add */ - if (sds->max_load * sds->busiest->sgp->power < - sds->busiest_load_per_task * SCHED_POWER_SCALE) - tmp = (sds->max_load * sds->busiest->sgp->power) / - sds->this->sgp->power; - else - tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) / - sds->this->sgp->power; - pwr_move += sds->this->sgp->power * - min(sds->this_load_per_task, sds->this_load + tmp); + if (busiest->avg_load * busiest->group_power < + busiest->load_per_task * SCHED_POWER_SCALE) { + tmp = (busiest->avg_load * busiest->group_power) / + local->group_power; + } else { + tmp = (busiest->load_per_task * SCHED_POWER_SCALE) / + local->group_power; + } + pwr_move += local->group_power * + min(local->load_per_task, local->avg_load + tmp); pwr_move /= SCHED_POWER_SCALE; /* Move if we gain throughput */ if (pwr_move > pwr_now) - env->imbalance = sds->busiest_load_per_task; + env->imbalance = busiest->load_per_task; } /** @@ -4846,11 +4877,18 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds) static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds) { unsigned long max_pull, load_above_capacity = ~0UL; + struct sg_lb_stats *local, *busiest; + + local = &sds->local_stat; + busiest = &sds->busiest_stat; - 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); + if (busiest->group_imb) { + /* + * In the group_imb case we cannot rely on group-wide averages + * to ensure cpu-load equilibrium, look at wider averages. XXX + */ + busiest->load_per_task = + min(busiest->load_per_task, sds->avg_load); } /* @@ -4858,21 +4896,22 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * max load less than avg load(as we skip the groups at or below * its cpu_power, while calculating max_load..) */ - if (sds->max_load < sds->avg_load) { + if (busiest->avg_load < sds->avg_load) { env->imbalance = 0; return fix_small_imbalance(env, sds); } - if (!sds->group_imb) { + if (!busiest->group_imb) { /* * Don't want to pull so many tasks that a group would go idle. + * Except of course for the group_imb case, since then we might + * have to drop below capacity to reach cpu-load equilibrium. */ - load_above_capacity = (sds->busiest_nr_running - - sds->busiest_group_capacity); + load_above_capacity = + (busiest->sum_nr_running - busiest->group_capacity); load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE); - - load_above_capacity /= sds->busiest->sgp->power; + load_above_capacity /= busiest->group_power; } /* @@ -4882,15 +4921,14 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * 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); + max_pull = min(busiest->avg_load - sds->avg_load, load_above_capacity); /* How much load to actually move to equalise the imbalance */ - env->imbalance = min(max_pull * sds->busiest->sgp->power, - (sds->avg_load - sds->this_load) * sds->this->sgp->power) - / SCHED_POWER_SCALE; + env->imbalance = min( + max_pull * busiest->group_power, + (sds->avg_load - local->avg_load) * local->group_power + ) / SCHED_POWER_SCALE; /* * if *imbalance is less than the average load per runnable task @@ -4898,9 +4936,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * a think about bumping its value to force at least one task to be * moved */ - if (env->imbalance < sds->busiest_load_per_task) + if (env->imbalance < busiest->load_per_task) return fix_small_imbalance(env, sds); - } /******* find_busiest_group() helpers end here *********************/ @@ -4916,69 +4953,62 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s * to restore balance. * * @env: The load balancing environment. - * @balance: Pointer to a variable indicating if this_cpu - * is the appropriate cpu to perform load balancing at this_level. * * Return: - The busiest group if imbalance exists. * - If no imbalance and user has opted for power-savings balance, * return the least loaded group whose CPUs can be * put to idle by rebalancing its tasks onto our group. */ -static struct sched_group * -find_busiest_group(struct lb_env *env, int *balance) +static struct sched_group *find_busiest_group(struct lb_env *env) { + struct sg_lb_stats *local, *busiest; struct sd_lb_stats sds; - memset(&sds, 0, sizeof(sds)); + init_sd_lb_stats(&sds); /* * Compute the various statistics relavent for load balancing at * this level. */ - update_sd_lb_stats(env, balance, &sds); - - /* - * this_cpu is not the appropriate cpu to perform load balancing at - * this level. - */ - if (!(*balance)) - goto ret; + update_sd_lb_stats(env, &sds); + local = &sds.local_stat; + busiest = &sds.busiest_stat; if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) && check_asym_packing(env, &sds)) return sds.busiest; /* There is no busy sibling group to pull tasks from */ - if (!sds.busiest || sds.busiest_nr_running == 0) + if (!sds.busiest || busiest->sum_nr_running == 0) goto out_balanced; sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr; /* * If the busiest group is imbalanced the below checks don't - * work because they assumes all things are equal, which typically + * work because they assume all things are equal, which typically * isn't true due to cpus_allowed constraints and the like. */ - if (sds.group_imb) + if (busiest->group_imb) goto force_balance; /* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */ - if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity && - !sds.busiest_has_capacity) + if (env->idle == CPU_NEWLY_IDLE && local->group_has_capacity && + !busiest->group_has_capacity) goto force_balance; /* * If the local group is more busy than the selected busiest group * don't try and pull any tasks. */ - if (sds.this_load >= sds.max_load) + if (local->avg_load >= busiest->avg_load) goto out_balanced; /* * Don't pull any tasks if this group is already above the domain * average load. */ - if (sds.this_load >= sds.avg_load) + if (local->avg_load >= sds.avg_load) goto out_balanced; if (env->idle == CPU_IDLE) { @@ -4988,15 +5018,16 @@ find_busiest_group(struct lb_env *env, int *balance) * there is no imbalance between this and busiest group * wrt to idle cpu's, it is balanced. */ - if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) && - sds.busiest_nr_running <= sds.busiest_group_weight) + if ((local->idle_cpus < busiest->idle_cpus) && + busiest->sum_nr_running <= busiest->group_weight) goto out_balanced; } else { /* * In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use * imbalance_pct to be conservative. */ - if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load) + if (100 * busiest->avg_load <= + env->sd->imbalance_pct * local->avg_load) goto out_balanced; } @@ -5006,7 +5037,6 @@ force_balance: return sds.busiest; out_balanced: -ret: env->imbalance = 0; return NULL; } @@ -5018,10 +5048,10 @@ static struct rq *find_busiest_queue(struct lb_env *env, struct sched_group *group) { struct rq *busiest = NULL, *rq; - unsigned long max_load = 0; + unsigned long busiest_load = 0, busiest_power = 1; int i; - for_each_cpu(i, sched_group_cpus(group)) { + for_each_cpu_and(i, sched_group_cpus(group), env->cpus) { unsigned long power = power_of(i); unsigned long capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE); @@ -5030,9 +5060,6 @@ static struct rq *find_busiest_queue(struct lb_env *env, if (!capacity) capacity = fix_small_capacity(env->sd, group); - if (!cpumask_test_cpu(i, env->cpus)) - continue; - rq = cpu_rq(i); wl = weighted_cpuload(i); @@ -5048,11 +5075,15 @@ static struct rq *find_busiest_queue(struct lb_env *env, * the weighted_cpuload() scaled with the cpu power, so that * the load can be moved away from the cpu that is potentially * running at a lower capacity. + * + * Thus we're looking for max(wl_i / power_i), crosswise + * multiplication to rid ourselves of the division works out + * to: wl_i * power_j > wl_j * power_i; where j is our + * previous maximum. */ - wl = (wl * SCHED_POWER_SCALE) / power; - - if (wl > max_load) { - max_load = wl; + if (wl * busiest_power > busiest_load * power) { + busiest_load = wl; + busiest_power = power; busiest = rq; } } @@ -5089,13 +5120,47 @@ static int need_active_balance(struct lb_env *env) static int active_load_balance_cpu_stop(void *data); +static int should_we_balance(struct lb_env *env) +{ + struct sched_group *sg = env->sd->groups; + struct cpumask *sg_cpus, *sg_mask; + int cpu, balance_cpu = -1; + + /* + * In the newly idle case, we will allow all the cpu's + * to do the newly idle load balance. + */ + if (env->idle == CPU_NEWLY_IDLE) + return 1; + + sg_cpus = sched_group_cpus(sg); + sg_mask = sched_group_mask(sg); + /* Try to find first idle cpu */ + for_each_cpu_and(cpu, sg_cpus, env->cpus) { + if (!cpumask_test_cpu(cpu, sg_mask) || !idle_cpu(cpu)) + continue; + + balance_cpu = cpu; + break; + } + + if (balance_cpu == -1) + balance_cpu = group_balance_cpu(sg); + + /* + * First idle cpu or the first cpu(busiest) in this sched group + * is eligible for doing load balancing at this and above domains. + */ + return balance_cpu != env->dst_cpu; +} + /* * Check this_cpu to ensure it is balanced within domain. Attempt to move * tasks if there is an imbalance. */ static int load_balance(int this_cpu, struct rq *this_rq, struct sched_domain *sd, enum cpu_idle_type idle, - int *balance) + int *continue_balancing) { int ld_moved, cur_ld_moved, active_balance = 0; struct sched_group *group; @@ -5125,11 +5190,12 @@ static int load_balance(int this_cpu, struct rq *this_rq, schedstat_inc(sd, lb_count[idle]); redo: - group = find_busiest_group(&env, balance); - - if (*balance == 0) + if (!should_we_balance(&env)) { + *continue_balancing = 0; goto out_balanced; + } + group = find_busiest_group(&env); if (!group) { schedstat_inc(sd, lb_nobusyg[idle]); goto out_balanced; @@ -5341,7 +5407,7 @@ void idle_balance(int this_cpu, struct rq *this_rq) rcu_read_lock(); for_each_domain(this_cpu, sd) { unsigned long interval; - int balance = 1; + int continue_balancing = 1; if (!(sd->flags & SD_LOAD_BALANCE)) continue; @@ -5349,7 +5415,8 @@ void idle_balance(int this_cpu, struct rq *this_rq) if (sd->flags & SD_BALANCE_NEWIDLE) { /* If we've pulled tasks over stop searching: */ pulled_task = load_balance(this_cpu, this_rq, - sd, CPU_NEWLY_IDLE, &balance); + sd, CPU_NEWLY_IDLE, + &continue_balancing); } interval = msecs_to_jiffies(sd->balance_interval); @@ -5587,7 +5654,7 @@ void update_max_interval(void) */ static void rebalance_domains(int cpu, enum cpu_idle_type idle) { - int balance = 1; + int continue_balancing = 1; struct rq *rq = cpu_rq(cpu); unsigned long interval; struct sched_domain *sd; @@ -5619,7 +5686,7 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle) } if (time_after_eq(jiffies, sd->last_balance + interval)) { - if (load_balance(cpu, rq, sd, idle, &balance)) { + if (load_balance(cpu, rq, sd, idle, &continue_balancing)) { /* * The LBF_SOME_PINNED logic could have changed * env->dst_cpu, so we can't know our idle @@ -5642,7 +5709,7 @@ out: * CPU in our sched group which is doing load balancing more * actively. */ - if (!balance) + if (!continue_balancing) break; } rcu_read_unlock(); @@ -5938,11 +6005,9 @@ static void switched_from_fair(struct rq *rq, struct task_struct *p) * and ensure we don't carry in an old decay_count if we * switch back. */ - if (p->se.avg.decay_count) { - struct cfs_rq *cfs_rq = cfs_rq_of(&p->se); - __synchronize_entity_decay(&p->se); - subtract_blocked_load_contrib(cfs_rq, - p->se.avg.load_avg_contrib); + if (se->avg.decay_count) { + __synchronize_entity_decay(se); + subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib); } #endif } diff --git a/kernel/smp.c b/kernel/smp.c index b1c9034..449b707 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -186,25 +186,13 @@ void generic_smp_call_function_single_interrupt(void) while (!list_empty(&list)) { struct call_single_data *csd; - unsigned int csd_flags; csd = list_entry(list.next, struct call_single_data, list); list_del(&csd->list); - /* - * 'csd' can be invalid after this call if flags == 0 - * (when called through generic_exec_single()), - * so save them away before making the call: - */ - csd_flags = csd->flags; - csd->func(csd->info); - /* - * Unlocked CSDs are valid through generic_exec_single(): - */ - if (csd_flags & CSD_FLAG_LOCK) - csd_unlock(csd); + csd_unlock(csd); } } |