sched: Let 'struct sched_group_power' care about CPU capacity

It is better not to think about compute capacity as being equivalent
to "CPU power".  The upcoming "power aware" scheduler work may create
confusion with the notion of energy consumption if "power" is used too
liberally.

Since struct sched_group_power is really about compute capacity of sched
groups, let's rename it to struct sched_group_capacity. Similarly sgp
becomes sgc. Related variables and functions dealing with groups are also
adjusted accordingly.

Signed-off-by: Nicolas Pitre <nico@linaro.org>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: Morten Rasmussen <morten.rasmussen@arm.com>
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: linaro-kernel@lists.linaro.org
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: linux-kernel@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-5yeix833vvgf2uyj5o36hpu9@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 66 insertions, 65 deletions

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e401e446e87c..36bd4d23fca8 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4369,8 +4369,8 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
 			avg_load += load;
 		}
 
-		/* Adjust by relative CPU power of the group */
-		avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
+		/* Adjust by relative CPU capacity of the group */
+		avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgc->capacity;
 
 		if (local_group) {
 			this_load = avg_load;
@@ -5532,7 +5532,7 @@ struct sg_lb_stats {
 	unsigned long group_load; /* Total load over the CPUs of the group */
 	unsigned long sum_weighted_load; /* Weighted load of group's tasks */
 	unsigned long load_per_task;
-	unsigned long group_power;
+	unsigned long group_capacity;
 	unsigned int sum_nr_running; /* Nr tasks running in the group */
 	unsigned int group_capacity_factor;
 	unsigned int idle_cpus;
@@ -5553,7 +5553,7 @@ 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 total_capacity;	/* Total capacity 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 */
@@ -5572,7 +5572,7 @@ static inline void init_sd_lb_stats(struct sd_lb_stats *sds)
 		.busiest = NULL,
 		.local = NULL,
 		.total_load = 0UL,
-		.total_pwr = 0UL,
+		.total_capacity = 0UL,
 		.busiest_stat = {
 			.avg_load = 0UL,
 		},
@@ -5681,7 +5681,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
 		power >>= SCHED_POWER_SHIFT;
 	}
 
-	sdg->sgp->power_orig = power;
+	sdg->sgc->capacity_orig = power;
 
 	if (sched_feat(ARCH_POWER))
 		power *= arch_scale_freq_power(sd, cpu);
@@ -5697,26 +5697,26 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
 		power = 1;
 
 	cpu_rq(cpu)->cpu_power = power;
-	sdg->sgp->power = power;
+	sdg->sgc->capacity = power;
 }
 
-void update_group_power(struct sched_domain *sd, int cpu)
+void update_group_capacity(struct sched_domain *sd, int cpu)
 {
 	struct sched_domain *child = sd->child;
 	struct sched_group *group, *sdg = sd->groups;
-	unsigned long power, power_orig;
+	unsigned long capacity, capacity_orig;
 	unsigned long interval;
 
 	interval = msecs_to_jiffies(sd->balance_interval);
 	interval = clamp(interval, 1UL, max_load_balance_interval);
-	sdg->sgp->next_update = jiffies + interval;
+	sdg->sgc->next_update = jiffies + interval;
 
 	if (!child) {
 		update_cpu_power(sd, cpu);
 		return;
 	}
 
-	power_orig = power = 0;
+	capacity_orig = capacity = 0;
 
 	if (child->flags & SD_OVERLAP) {
 		/*
@@ -5725,31 +5725,31 @@ void update_group_power(struct sched_domain *sd, int cpu)
 		 */
 
 		for_each_cpu(cpu, sched_group_cpus(sdg)) {
-			struct sched_group_power *sgp;
+			struct sched_group_capacity *sgc;
 			struct rq *rq = cpu_rq(cpu);
 
 			/*
-			 * build_sched_domains() -> init_sched_groups_power()
+			 * build_sched_domains() -> init_sched_groups_capacity()
 			 * gets here before we've attached the domains to the
 			 * runqueues.
 			 *
 			 * Use power_of(), which is set irrespective of domains
 			 * in update_cpu_power().
 			 *
-			 * This avoids power/power_orig from being 0 and
+			 * This avoids capacity/capacity_orig from being 0 and
 			 * causing divide-by-zero issues on boot.
 			 *
-			 * Runtime updates will correct power_orig.
+			 * Runtime updates will correct capacity_orig.
 			 */
 			if (unlikely(!rq->sd)) {
-				power_orig += power_of(cpu);
-				power += power_of(cpu);
+				capacity_orig += power_of(cpu);
+				capacity += power_of(cpu);
 				continue;
 			}
 
-			sgp = rq->sd->groups->sgp;
-			power_orig += sgp->power_orig;
-			power += sgp->power;
+			sgc = rq->sd->groups->sgc;
+			capacity_orig += sgc->capacity_orig;
+			capacity += sgc->capacity;
 		}
 	} else  {
 		/*
@@ -5759,14 +5759,14 @@ void update_group_power(struct sched_domain *sd, int cpu)
 
 		group = child->groups;
 		do {
-			power_orig += group->sgp->power_orig;
-			power += group->sgp->power;
+			capacity_orig += group->sgc->capacity_orig;
+			capacity += group->sgc->capacity;
 			group = group->next;
 		} while (group != child->groups);
 	}
 
-	sdg->sgp->power_orig = power_orig;
-	sdg->sgp->power = power;
+	sdg->sgc->capacity_orig = capacity_orig;
+	sdg->sgc->capacity = capacity;
 }
 
 /*
@@ -5786,9 +5786,9 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
 		return 0;
 
 	/*
-	 * If ~90% of the cpu_power is still there, we're good.
+	 * If ~90% of the cpu_capacity is still there, we're good.
 	 */
-	if (group->sgp->power * 32 > group->sgp->power_orig * 29)
+	if (group->sgc->capacity * 32 > group->sgc->capacity_orig * 29)
 		return 1;
 
 	return 0;
@@ -5825,7 +5825,7 @@ fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
 
 static inline int sg_imbalanced(struct sched_group *group)
 {
-	return group->sgp->imbalance;
+	return group->sgc->imbalance;
 }
 
 /*
@@ -5833,22 +5833,23 @@ static inline int sg_imbalanced(struct sched_group *group)
  *
  * Avoid the issue where N*frac(smt_power) >= 1 creates 'phantom' cores by
  * first dividing out the smt factor and computing the actual number of cores
- * and limit power unit capacity with that.
+ * and limit unit capacity with that.
  */
 static inline int sg_capacity_factor(struct lb_env *env, struct sched_group *group)
 {
 	unsigned int capacity_factor, smt, cpus;
-	unsigned int power, power_orig;
+	unsigned int capacity, capacity_orig;
 
-	power = group->sgp->power;
-	power_orig = group->sgp->power_orig;
+	capacity = group->sgc->capacity;
+	capacity_orig = group->sgc->capacity_orig;
 	cpus = group->group_weight;
 
-	/* smt := ceil(cpus / power), assumes: 1 < smt_power < 2 */
-	smt = DIV_ROUND_UP(SCHED_POWER_SCALE * cpus, power_orig);
+	/* smt := ceil(cpus / capacity), assumes: 1 < smt_capacity < 2 */
+	smt = DIV_ROUND_UP(SCHED_POWER_SCALE * cpus, capacity_orig);
 	capacity_factor = cpus / smt; /* cores */
 
-	capacity_factor = min_t(unsigned, capacity_factor, DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE));
+	capacity_factor = min_t(unsigned,
+		capacity_factor, DIV_ROUND_CLOSEST(capacity, SCHED_POWER_SCALE));
 	if (!capacity_factor)
 		capacity_factor = fix_small_capacity(env->sd, group);
 
@@ -5892,9 +5893,9 @@ static inline void update_sg_lb_stats(struct lb_env *env,
 			sgs->idle_cpus++;
 	}
 
-	/* Adjust by relative CPU power of the group */
-	sgs->group_power = group->sgp->power;
-	sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_power;
+	/* Adjust by relative CPU capacity of the group */
+	sgs->group_capacity = group->sgc->capacity;
+	sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / sgs->group_capacity;
 
 	if (sgs->sum_nr_running)
 		sgs->load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
@@ -6009,8 +6010,8 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 			sgs = &sds->local_stat;
 
 			if (env->idle != CPU_NEWLY_IDLE ||
-			    time_after_eq(jiffies, sg->sgp->next_update))
-				update_group_power(env->sd, env->dst_cpu);
+			    time_after_eq(jiffies, sg->sgc->next_update))
+				update_group_capacity(env->sd, env->dst_cpu);
 		}
 
 		update_sg_lb_stats(env, sg, load_idx, local_group, sgs);
@@ -6040,7 +6041,7 @@ static inline void update_sd_lb_stats(struct lb_env *env, struct sd_lb_stats *sd
 next_group:
 		/* Now, start updating sd_lb_stats */
 		sds->total_load += sgs->group_load;
-		sds->total_pwr += sgs->group_power;
+		sds->total_capacity += sgs->group_capacity;
 
 		sg = sg->next;
 	} while (sg != env->sd->groups);
@@ -6087,7 +6088,7 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
 		return 0;
 
 	env->imbalance = DIV_ROUND_CLOSEST(
-		sds->busiest_stat.avg_load * sds->busiest_stat.group_power,
+		sds->busiest_stat.avg_load * sds->busiest_stat.group_capacity,
 		SCHED_POWER_SCALE);
 
 	return 1;
@@ -6103,7 +6104,7 @@ static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
 static inline
 void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
 {
-	unsigned long tmp, pwr_now = 0, pwr_move = 0;
+	unsigned long tmp, capa_now = 0, capa_move = 0;
 	unsigned int imbn = 2;
 	unsigned long scaled_busy_load_per_task;
 	struct sg_lb_stats *local, *busiest;
@@ -6118,7 +6119,7 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
 
 	scaled_busy_load_per_task =
 		(busiest->load_per_task * SCHED_POWER_SCALE) /
-		busiest->group_power;
+		busiest->group_capacity;
 
 	if (busiest->avg_load + scaled_busy_load_per_task >=
 	    local->avg_load + (scaled_busy_load_per_task * imbn)) {
@@ -6132,34 +6133,34 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
 	 * moving them.
 	 */
 
-	pwr_now += busiest->group_power *
+	capa_now += busiest->group_capacity *
 			min(busiest->load_per_task, busiest->avg_load);
-	pwr_now += local->group_power *
+	capa_now += local->group_capacity *
 			min(local->load_per_task, local->avg_load);
-	pwr_now /= SCHED_POWER_SCALE;
+	capa_now /= SCHED_POWER_SCALE;
 
 	/* Amount of load we'd subtract */
 	if (busiest->avg_load > scaled_busy_load_per_task) {
-		pwr_move += busiest->group_power *
+		capa_move += busiest->group_capacity *
 			    min(busiest->load_per_task,
 				busiest->avg_load - scaled_busy_load_per_task);
 	}
 
 	/* Amount of load we'd add */
-	if (busiest->avg_load * busiest->group_power <
+	if (busiest->avg_load * busiest->group_capacity <
 	    busiest->load_per_task * SCHED_POWER_SCALE) {
-		tmp = (busiest->avg_load * busiest->group_power) /
-		      local->group_power;
+		tmp = (busiest->avg_load * busiest->group_capacity) /
+		      local->group_capacity;
 	} else {
 		tmp = (busiest->load_per_task * SCHED_POWER_SCALE) /
-		      local->group_power;
+		      local->group_capacity;
 	}
-	pwr_move += local->group_power *
+	capa_move += local->group_capacity *
 		    min(local->load_per_task, local->avg_load + tmp);
-	pwr_move /= SCHED_POWER_SCALE;
+	capa_move /= SCHED_POWER_SCALE;
 
 	/* Move if we gain throughput */
-	if (pwr_move > pwr_now)
+	if (capa_move > capa_now)
 		env->imbalance = busiest->load_per_task;
 }
 
@@ -6207,7 +6208,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
 			(busiest->sum_nr_running - busiest->group_capacity_factor);
 
 		load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
-		load_above_capacity /= busiest->group_power;
+		load_above_capacity /= busiest->group_capacity;
 	}
 
 	/*
@@ -6222,8 +6223,8 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
 
 	/* How much load to actually move to equalise the imbalance */
 	env->imbalance = min(
-		max_pull * busiest->group_power,
-		(sds->avg_load - local->avg_load) * local->group_power
+		max_pull * busiest->group_capacity,
+		(sds->avg_load - local->avg_load) * local->group_capacity
 	) / SCHED_POWER_SCALE;
 
 	/*
@@ -6278,7 +6279,7 @@ static struct sched_group *find_busiest_group(struct lb_env *env)
 	if (!sds.busiest || busiest->sum_nr_running == 0)
 		goto out_balanced;
 
-	sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
+	sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_capacity;
 
 	/*
 	 * If the busiest group is imbalanced the below checks don't
@@ -6611,7 +6612,7 @@ more_balance:
 		 * We failed to reach balance because of affinity.
 		 */
 		if (sd_parent) {
-			int *group_imbalance = &sd_parent->groups->sgp->imbalance;
+			int *group_imbalance = &sd_parent->groups->sgc->imbalance;
 
 			if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) {
 				*group_imbalance = 1;
@@ -6998,7 +6999,7 @@ static inline void set_cpu_sd_state_busy(void)
 		goto unlock;
 	sd->nohz_idle = 0;
 
-	atomic_inc(&sd->groups->sgp->nr_busy_cpus);
+	atomic_inc(&sd->groups->sgc->nr_busy_cpus);
 unlock:
 	rcu_read_unlock();
 }
@@ -7015,7 +7016,7 @@ void set_cpu_sd_state_idle(void)
 		goto unlock;
 	sd->nohz_idle = 1;
 
-	atomic_dec(&sd->groups->sgp->nr_busy_cpus);
+	atomic_dec(&sd->groups->sgc->nr_busy_cpus);
 unlock:
 	rcu_read_unlock();
 }
@@ -7219,7 +7220,7 @@ end:
  * of an idle cpu is the system.
  *   - This rq has more than one task.
  *   - At any scheduler domain level, this cpu's scheduler group has multiple
- *     busy cpu's exceeding the group's power.
+ *     busy cpu's exceeding the group's capacity.
  *   - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
  *     domain span are idle.
  */
@@ -7227,7 +7228,7 @@ static inline int nohz_kick_needed(struct rq *rq)
 {
 	unsigned long now = jiffies;
 	struct sched_domain *sd;
-	struct sched_group_power *sgp;
+	struct sched_group_capacity *sgc;
 	int nr_busy, cpu = rq->cpu;
 
 	if (unlikely(rq->idle_balance))
@@ -7257,8 +7258,8 @@ static inline int nohz_kick_needed(struct rq *rq)
 	sd = rcu_dereference(per_cpu(sd_busy, cpu));
 
 	if (sd) {
-		sgp = sd->groups->sgp;
-		nr_busy = atomic_read(&sgp->nr_busy_cpus);
+		sgc = sd->groups->sgc;
+		nr_busy = atomic_read(&sgc->nr_busy_cpus);
 
 		if (nr_busy > 1)
 			goto need_kick_unlock;