sched: Remove remaining dubious usage of "power"

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.

This is the remaining "power" -> "capacity" rename for local symbols.
Those symbols visible to the rest of the kernel are not included yet.

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-yyyhohzhkwnaotr3lx8zd5aa@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

@@ -5764,7 +5764,7 @@ static int get_group(int cpu, struct sd_data *sdd, struct sched_group **sg)
 /*
  * build_sched_groups will build a circular linked list of the groups
  * covered by the given span, and will set each group's ->cpumask correctly,
- * and ->cpu_power to 0.
+ * and ->cpu_capacity to 0.
  *
  * Assumes the sched_domain tree is fully constructed
  */
@@ -6471,7 +6471,7 @@ static int build_sched_domains(const struct cpumask *cpu_map,
 		}
 	}
 
-	/* Calculate CPU power for physical packages and nodes */
+	/* Calculate CPU capacity for physical packages and nodes */
 	for (i = nr_cpumask_bits-1; i >= 0; i--) {
 		if (!cpumask_test_cpu(i, cpu_map))
 			continue;
@@ -6921,7 +6921,7 @@ void __init sched_init(void)
 #ifdef CONFIG_SMP
 		rq->sd = NULL;
 		rq->rd = NULL;
-		rq->cpu_power = SCHED_POWER_SCALE;
+		rq->cpu_capacity = SCHED_POWER_SCALE;
 		rq->post_schedule = 0;
 		rq->active_balance = 0;
 		rq->next_balance = jiffies;

kernel/sched/fair.c

@@ -1017,7 +1017,7 @@ bool should_numa_migrate_memory(struct task_struct *p, struct page * page,
 static unsigned long weighted_cpuload(const int cpu);
 static unsigned long source_load(int cpu, int type);
 static unsigned long target_load(int cpu, int type);
-static unsigned long power_of(int cpu);
+static unsigned long capacity_of(int cpu);
 static long effective_load(struct task_group *tg, int cpu, long wl, long wg);
 
 /* Cached statistics for all CPUs within a node */
@@ -1046,7 +1046,7 @@ static void update_numa_stats(struct numa_stats *ns, int nid)
 
 		ns->nr_running += rq->nr_running;
 		ns->load += weighted_cpuload(cpu);
-		ns->compute_capacity += power_of(cpu);
+		ns->compute_capacity += capacity_of(cpu);
 
 		cpus++;
 	}
@@ -1214,7 +1214,7 @@ balance:
 	orig_dst_load = env->dst_stats.load;
 	orig_src_load = env->src_stats.load;
 
-	/* XXX missing power terms */
+	/* XXX missing capacity terms */
 	load = task_h_load(env->p);
 	dst_load = orig_dst_load + load;
 	src_load = orig_src_load - load;
@@ -4043,9 +4043,9 @@ static unsigned long target_load(int cpu, int type)
 	return max(rq->cpu_load[type-1], total);
 }
 
-static unsigned long power_of(int cpu)
+static unsigned long capacity_of(int cpu)
 {
-	return cpu_rq(cpu)->cpu_power;
+	return cpu_rq(cpu)->cpu_capacity;
 }
 
 static unsigned long cpu_avg_load_per_task(int cpu)
@@ -4288,12 +4288,12 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
 		s64 this_eff_load, prev_eff_load;
 
 		this_eff_load = 100;
-		this_eff_load *= power_of(prev_cpu);
+		this_eff_load *= capacity_of(prev_cpu);
 		this_eff_load *= this_load +
 			effective_load(tg, this_cpu, weight, weight);
 
 		prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
-		prev_eff_load *= power_of(this_cpu);
+		prev_eff_load *= capacity_of(this_cpu);
 		prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
 
 		balanced = this_eff_load <= prev_eff_load;
@@ -4950,14 +4950,14 @@ static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preemp
  *
  *   W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0               (3)
  *
- * P_i is the cpu power (or compute capacity) of cpu i, typically it is the
+ * C_i is the compute capacity of cpu i, typically it is the
  * fraction of 'recent' time available for SCHED_OTHER task execution. But it
  * can also include other factors [XXX].
  *
  * To achieve this balance we define a measure of imbalance which follows
  * directly from (1):
  *
- *   imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j }    (4)
+ *   imb_i,j = max{ avg(W/C), W_i/C_i } - min{ avg(W/C), W_j/C_j }    (4)
  *
  * We them move tasks around to minimize the imbalance. In the continuous
  * function space it is obvious this converges, in the discrete case we get
@@ -5607,17 +5607,17 @@ static inline int get_sd_load_idx(struct sched_domain *sd,
 	return load_idx;
 }
 
-static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
+static unsigned long default_scale_capacity(struct sched_domain *sd, int cpu)
 {
 	return SCHED_POWER_SCALE;
 }
 
 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
 {
-	return default_scale_freq_power(sd, cpu);
+	return default_scale_capacity(sd, cpu);
 }
 
-static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
+static unsigned long default_scale_smt_capacity(struct sched_domain *sd, int cpu)
 {
 	unsigned long weight = sd->span_weight;
 	unsigned long smt_gain = sd->smt_gain;
@@ -5629,10 +5629,10 @@ static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
 
 unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
 {
-	return default_scale_smt_power(sd, cpu);
+	return default_scale_smt_capacity(sd, cpu);
 }
 
-static unsigned long scale_rt_power(int cpu)
+static unsigned long scale_rt_capacity(int cpu)
 {
 	struct rq *rq = cpu_rq(cpu);
 	u64 total, available, age_stamp, avg;
@@ -5652,7 +5652,7 @@ static unsigned long scale_rt_power(int cpu)
 	total = sched_avg_period() + delta;
 
 	if (unlikely(total < avg)) {
-		/* Ensures that power won't end up being negative */
+		/* Ensures that capacity won't end up being negative */
 		available = 0;
 	} else {
 		available = total - avg;
@@ -5666,38 +5666,38 @@ static unsigned long scale_rt_power(int cpu)
 	return div_u64(available, total);
 }
 
-static void update_cpu_power(struct sched_domain *sd, int cpu)
+static void update_cpu_capacity(struct sched_domain *sd, int cpu)
 {
 	unsigned long weight = sd->span_weight;
-	unsigned long power = SCHED_POWER_SCALE;
+	unsigned long capacity = SCHED_POWER_SCALE;
 	struct sched_group *sdg = sd->groups;
 
 	if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
 		if (sched_feat(ARCH_POWER))
-			power *= arch_scale_smt_power(sd, cpu);
+			capacity *= arch_scale_smt_power(sd, cpu);
 		else
-			power *= default_scale_smt_power(sd, cpu);
+			capacity *= default_scale_smt_capacity(sd, cpu);
 
-		power >>= SCHED_POWER_SHIFT;
+		capacity >>= SCHED_POWER_SHIFT;
 	}
 
-	sdg->sgc->capacity_orig = power;
+	sdg->sgc->capacity_orig = capacity;
 
 	if (sched_feat(ARCH_POWER))
-		power *= arch_scale_freq_power(sd, cpu);
+		capacity *= arch_scale_freq_power(sd, cpu);
 	else
-		power *= default_scale_freq_power(sd, cpu);
+		capacity *= default_scale_capacity(sd, cpu);
 
-	power >>= SCHED_POWER_SHIFT;
+	capacity >>= SCHED_POWER_SHIFT;
 
-	power *= scale_rt_power(cpu);
-	power >>= SCHED_POWER_SHIFT;
+	capacity *= scale_rt_capacity(cpu);
+	capacity >>= SCHED_POWER_SHIFT;
 
-	if (!power)
-		power = 1;
+	if (!capacity)
+		capacity = 1;
 
-	cpu_rq(cpu)->cpu_power = power;
-	sdg->sgc->capacity = power;
+	cpu_rq(cpu)->cpu_capacity = capacity;
+	sdg->sgc->capacity = capacity;
 }
 
 void update_group_capacity(struct sched_domain *sd, int cpu)
@@ -5712,7 +5712,7 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
 	sdg->sgc->next_update = jiffies + interval;
 
 	if (!child) {
-		update_cpu_power(sd, cpu);
+		update_cpu_capacity(sd, cpu);
 		return;
 	}
 
@@ -5733,8 +5733,8 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
 			 * gets here before we've attached the domains to the
 			 * runqueues.
 			 *
-			 * Use power_of(), which is set irrespective of domains
-			 * in update_cpu_power().
+			 * Use capacity_of(), which is set irrespective of domains
+			 * in update_cpu_capacity().
 			 *
 			 * This avoids capacity/capacity_orig from being 0 and
 			 * causing divide-by-zero issues on boot.
@@ -5742,8 +5742,8 @@ void update_group_capacity(struct sched_domain *sd, int cpu)
 			 * Runtime updates will correct capacity_orig.
 			 */
 			if (unlikely(!rq->sd)) {
-				capacity_orig += power_of(cpu);
-				capacity += power_of(cpu);
+				capacity_orig += capacity_of(cpu);
+				capacity += capacity_of(cpu);
 				continue;
 			}
 
@@ -5831,7 +5831,7 @@ static inline int sg_imbalanced(struct sched_group *group)
 /*
  * Compute the group capacity factor.
  *
- * Avoid the issue where N*frac(smt_power) >= 1 creates 'phantom' cores by
+ * Avoid the issue where N*frac(smt_capacity) >= 1 creates 'phantom' cores by
  * first dividing out the smt factor and computing the actual number of cores
  * and limit unit capacity with that.
  */
@@ -6129,7 +6129,7 @@ void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
 
 	/*
 	 * OK, we don't have enough imbalance to justify moving tasks,
-	 * however we may be able to increase total CPU power used by
+	 * however we may be able to increase total CPU capacity used by
 	 * moving them.
 	 */
 
@@ -6190,7 +6190,7 @@ static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *s
 	/*
 	 * 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
-	 * its cpu_power, while calculating max_load..)
+	 * its cpu_capacity, while calculating max_load..)
 	 */
 	if (busiest->avg_load <= sds->avg_load ||
 	    local->avg_load >= sds->avg_load) {
@@ -6345,11 +6345,11 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 				     struct sched_group *group)
 {
 	struct rq *busiest = NULL, *rq;
-	unsigned long busiest_load = 0, busiest_power = 1;
+	unsigned long busiest_load = 0, busiest_capacity = 1;
 	int i;
 
 	for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
-		unsigned long power, capacity_factor, wl;
+		unsigned long capacity, capacity_factor, wl;
 		enum fbq_type rt;
 
 		rq = cpu_rq(i);
@@ -6377,8 +6377,8 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 		if (rt > env->fbq_type)
 			continue;
 
-		power = power_of(i);
-		capacity_factor = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
+		capacity = capacity_of(i);
+		capacity_factor = DIV_ROUND_CLOSEST(capacity, SCHED_POWER_SCALE);
 		if (!capacity_factor)
 			capacity_factor = fix_small_capacity(env->sd, group);
 
@@ -6386,25 +6386,25 @@ static struct rq *find_busiest_queue(struct lb_env *env,
 
 		/*
 		 * When comparing with imbalance, use weighted_cpuload()
-		 * which is not scaled with the cpu power.
+		 * which is not scaled with the cpu capacity.
 		 */
 		if (capacity_factor && rq->nr_running == 1 && wl > env->imbalance)
 			continue;
 
 		/*
 		 * For the load comparisons with the other cpu's, consider
-		 * 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.
+		 * the weighted_cpuload() scaled with the cpu capacity, 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
+		 * Thus we're looking for max(wl_i / capacity_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.
+		 * to: wl_i * capacity_j > wl_j * capacity_i;  where j is
+		 * our previous maximum.
 		 */
-		if (wl * busiest_power > busiest_load * power) {
+		if (wl * busiest_capacity > busiest_load * capacity) {
 			busiest_load = wl;
-			busiest_power = power;
+			busiest_capacity = capacity;
 			busiest = rq;
 		}
 	}

kernel/sched/sched.h

@@ -567,7 +567,7 @@ struct rq {
 	struct root_domain *rd;
 	struct sched_domain *sd;
 
-	unsigned long cpu_power;
+	unsigned long cpu_capacity;
 
 	unsigned char idle_balance;
 	/* For active balancing */