sched: Introduce SCHED_POWER_SCALE to scale cpu_power calculations

SCHED_LOAD_SCALE is used to increase nice resolution and to
scale cpu_power calculations in the scheduler. This patch
introduces SCHED_POWER_SCALE and converts all uses of
SCHED_LOAD_SCALE for scaling cpu_power to use SCHED_POWER_SCALE
instead.

This is a preparatory patch for increasing the resolution of
SCHED_LOAD_SCALE, and there is no need to increase resolution
for cpu_power calculations.

Signed-off-by: Nikhil Rao <ncrao@google.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Cc: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
Cc: Stephan Barwolf <stephan.baerwolf@tu-ilmenau.de>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/1305738580-9924-3-git-send-email-ncrao@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>

3 files changed, 37 insertions, 32 deletions

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 12211e1666e2..f2f440221b70 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -788,17 +788,20 @@ enum cpu_idle_type {
 };
 
 /*
- * sched-domains (multiprocessor balancing) declarations:
- */
-
-/*
  * Increase resolution of nice-level calculations:
  */
 #define SCHED_LOAD_SHIFT        10
 #define SCHED_LOAD_SCALE        (1L << SCHED_LOAD_SHIFT)
 
-#define SCHED_LOAD_SCALE_FUZZ   SCHED_LOAD_SCALE
+/*
+ * Increase resolution of cpu_power calculations
+ */
+#define SCHED_POWER_SHIFT       10
+#define SCHED_POWER_SCALE       (1L << SCHED_POWER_SHIFT)
 
+/*
+ * sched-domains (multiprocessor balancing) declarations:
+ */
 #ifdef CONFIG_SMP
 #define SD_LOAD_BALANCE         0x0001  /* Do load balancing on this domain. */
 #define SD_BALANCE_NEWIDLE      0x0002  /* Balance when about to become idle */
diff --git a/kernel/sched.c b/kernel/sched.c
index d036048b59a4..375e9c677d58 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -6530,7 +6530,7 @@ static int sched_domain_debug_one(struct sched_domain *sd, int cpu, int level,
                 cpulist_scnprintf(str, sizeof(str), sched_group_cpus(group));
 
                 printk(KERN_CONT " %s", str);
-                if (group->cpu_power != SCHED_LOAD_SCALE) {
+                if (group->cpu_power != SCHED_POWER_SCALE) {
                         printk(KERN_CONT " (cpu_power = %d)",
                                 group->cpu_power);
                 }
@@ -7905,7 +7905,7 @@ void __init sched_init(void)
 #ifdef CONFIG_SMP
                 rq->sd = NULL;
                 rq->rd = NULL;
-                rq->cpu_power = SCHED_LOAD_SCALE;
+                rq->cpu_power = SCHED_POWER_SCALE;
                 rq->post_schedule = 0;
                 rq->active_balance = 0;
                 rq->next_balance = jiffies;
diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 37f22626225e..e32a9b70ee9c 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1584,7 +1584,7 @@ find_idlest_group(struct sched_domain *sd, struct task_struct *p,
                 }
 
                 /* Adjust by relative CPU power of the group */
-                avg_load = (avg_load * SCHED_LOAD_SCALE) / group->cpu_power;
+                avg_load = (avg_load * SCHED_POWER_SCALE) / group->cpu_power;
 
                 if (local_group) {
                         this_load = avg_load;
@@ -1722,7 +1722,7 @@ select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
                                 nr_running += cpu_rq(i)->cfs.nr_running;
                         }
 
-                        capacity = DIV_ROUND_CLOSEST(power, SCHED_LOAD_SCALE);
+                        capacity = DIV_ROUND_CLOSEST(power, SCHED_POWER_SCALE);
 
                         if (tmp->flags & SD_POWERSAVINGS_BALANCE)
                                 nr_running /= 2;
@@ -2570,7 +2570,7 @@ static inline int check_power_save_busiest_group(struct sd_lb_stats *sds,
 
 unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
 {
-        return SCHED_LOAD_SCALE;
+        return SCHED_POWER_SCALE;
 }
 
 unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
@@ -2607,10 +2607,10 @@ unsigned long scale_rt_power(int cpu)
                 available = total - rq->rt_avg;
         }
 
-        if (unlikely((s64)total < SCHED_LOAD_SCALE))
-                total = SCHED_LOAD_SCALE;
+        if (unlikely((s64)total < SCHED_POWER_SCALE))
+                total = SCHED_POWER_SCALE;
 
-        total >>= SCHED_LOAD_SHIFT;
+        total >>= SCHED_POWER_SHIFT;
 
         return div_u64(available, total);
 }
@@ -2618,7 +2618,7 @@ unsigned long scale_rt_power(int cpu)
 static void update_cpu_power(struct sched_domain *sd, int cpu)
 {
         unsigned long weight = sd->span_weight;
-        unsigned long power = SCHED_LOAD_SCALE;
+        unsigned long power = SCHED_POWER_SCALE;
         struct sched_group *sdg = sd->groups;
 
         if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
@@ -2627,7 +2627,7 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
                 else
                         power *= default_scale_smt_power(sd, cpu);
 
-                power >>= SCHED_LOAD_SHIFT;
+                power >>= SCHED_POWER_SHIFT;
         }
 
         sdg->cpu_power_orig = power;
@@ -2637,10 +2637,10 @@ static void update_cpu_power(struct sched_domain *sd, int cpu)
         else
                 power *= default_scale_freq_power(sd, cpu);
 
-        power >>= SCHED_LOAD_SHIFT;
+        power >>= SCHED_POWER_SHIFT;
 
         power *= scale_rt_power(cpu);
-        power >>= SCHED_LOAD_SHIFT;
+        power >>= SCHED_POWER_SHIFT;
 
         if (!power)
                 power = 1;
@@ -2682,7 +2682,7 @@ static inline int
 fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
 {
         /*
-         * Only siblings can have significantly less than SCHED_LOAD_SCALE
+         * Only siblings can have significantly less than SCHED_POWER_SCALE
          */
         if (!(sd->flags & SD_SHARE_CPUPOWER))
                 return 0;
@@ -2770,7 +2770,7 @@ 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;
+        sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->cpu_power;
 
         /*
          * Consider the group unbalanced when the imbalance is larger
@@ -2787,7 +2787,8 @@ static inline void update_sg_lb_stats(struct sched_domain *sd,
         if ((max_cpu_load - min_cpu_load) >= avg_load_per_task && max_nr_running > 1)
                 sgs->group_imb = 1;
 
-        sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power, SCHED_LOAD_SCALE);
+        sgs->group_capacity = DIV_ROUND_CLOSEST(group->cpu_power,
+                                                SCHED_POWER_SCALE);
         if (!sgs->group_capacity)
                 sgs->group_capacity = fix_small_capacity(sd, group);
         sgs->group_weight = group->group_weight;
@@ -2961,7 +2962,7 @@ static int check_asym_packing(struct sched_domain *sd,
                 return 0;
 
         *imbalance = DIV_ROUND_CLOSEST(sds->max_load * sds->busiest->cpu_power,