sched/fair: Rewrite runnable load and utilization average tracking

[pandora-kernel.git] / include / linux / sched.h

diff --git a/include/linux/sched.h b/include/linux/sched.h
index 9c14465..44dca5b 100644 (file)
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1175,29 +1175,24 @@ struct load_weight {
        u32 inv_weight;
 };
 
+/*
+ * The load_avg/util_avg accumulates an infinite geometric series.
+ * 1) load_avg factors the amount of time that a sched_entity is
+ * runnable on a rq into its weight. For cfs_rq, it is the aggregated
+ * such weights of all runnable and blocked sched_entities.
+ * 2) util_avg factors frequency scaling into the amount of time
+ * that a sched_entity is running on a CPU, in the range [0..SCHED_LOAD_SCALE].
+ * For cfs_rq, it is the aggregated such times of all runnable and
+ * blocked sched_entities.
+ * The 64 bit load_sum can:
+ * 1) for cfs_rq, afford 4353082796 (=2^64/47742/88761) entities with
+ * the highest weight (=88761) always runnable, we should not overflow
+ * 2) for entity, support any load.weight always runnable
+ */
 struct sched_avg {
-       u64 last_runnable_update;
-       s64 decay_count;
-       /*
-        * utilization_avg_contrib describes the amount of time that a
-        * sched_entity is running on a CPU. It is based on running_avg_sum
-        * and is scaled in the range [0..SCHED_LOAD_SCALE].
-        * load_avg_contrib described the amount of time that a sched_entity
-        * is runnable on a rq. It is based on both runnable_avg_sum and the
-        * weight of the task.
-        */
-       unsigned long load_avg_contrib, utilization_avg_contrib;
-       /*
-        * These sums represent an infinite geometric series and so are bound
-        * above by 1024/(1-y).  Thus we only need a u32 to store them for all
-        * choices of y < 1-2^(-32)*1024.
-        * running_avg_sum reflects the time that the sched_entity is
-        * effectively running on the CPU.
-        * runnable_avg_sum represents the amount of time a sched_entity is on
-        * a runqueue which includes the running time that is monitored by
-        * running_avg_sum.
-        */
-       u32 runnable_avg_sum, avg_period, running_avg_sum;
+       u64 last_update_time, load_sum;
+       u32 util_sum, period_contrib;
+       unsigned long load_avg, util_avg;
 };
 
 #ifdef CONFIG_SCHEDSTATS
@@ -1263,7 +1258,7 @@ struct sched_entity {
 #endif
 
 #ifdef CONFIG_SMP
-       /* Per-entity load-tracking */
+       /* Per entity load average tracking */
        struct sched_avg        avg;
 #endif
 };