sched: clean up wakeup balancing, move wake_affine()

split out the affine-wakeup bits.

No code changed:

kernel/sched.o:

   text	   data	    bss	    dec	    hex	filename
  42521	   2858	    232	  45611	   b22b	sched.o.before
  42521	   2858	    232	  45611	   b22b	sched.o.after

md5:
   9d76738f1272aa82f0b7affd2f51df6b  sched.o.before.asm
   09b31c44e9aff8666f72773dc433e2df  sched.o.after.asm

(the md5's changed because stack slots changed and some registers
get scheduled by gcc in a different order - but otherwise the before
and after assembly is instruction for instruction equivalent.)

Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 75 insertions, 59 deletions

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f2cc59080efa..70679b266693 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -980,12 +980,59 @@ static inline int wake_idle(int cpu, struct task_struct *p)
 #endif
 
 #ifdef CONFIG_SMP
+
+static int
+wake_affine(struct rq *rq, struct sched_domain *this_sd, struct task_struct *p,
+            int cpu, int this_cpu, int sync, int idx,
+            unsigned long load, unsigned long this_load,
+            unsigned int imbalance)
+{
+        unsigned long tl = this_load;
+        unsigned long tl_per_task;
+
+        if (!(this_sd->flags & SD_WAKE_AFFINE))
+                return 0;
+
+        /*
+         * Attract cache-cold tasks on sync wakeups:
+         */
+        if (sync && !task_hot(p, rq->clock, this_sd))
+                return 1;
+
+        schedstat_inc(p, se.nr_wakeups_affine_attempts);
+        tl_per_task = cpu_avg_load_per_task(this_cpu);
+
+        /*
+         * If sync wakeup then subtract the (maximum possible)
+         * effect of the currently running task from the load
+         * of the current CPU:
+         */
+        if (sync)
+                tl -= current->se.load.weight;
+
+        if ((tl <= load && tl + target_load(cpu, idx) <= tl_per_task) ||
+                        100*(tl + p->se.load.weight) <= imbalance*load) {
+                /*
+                 * This domain has SD_WAKE_AFFINE and
+                 * p is cache cold in this domain, and
+                 * there is no bad imbalance.
+                 */
+                schedstat_inc(this_sd, ttwu_move_affine);
+                schedstat_inc(p, se.nr_wakeups_affine);
+
+                return 1;
+        }
+        return 0;
+}
+
 static int select_task_rq_fair(struct task_struct *p, int sync)
 {
-        int cpu, this_cpu;
-        struct rq *rq;
         struct sched_domain *sd, *this_sd = NULL;
-        int new_cpu;
+        unsigned long load, this_load;
+        int cpu, this_cpu, new_cpu;
+        unsigned int imbalance;
+        struct rq *rq;
+        int idx;
 
         cpu      = task_cpu(p);
         rq       = task_rq(p);
@@ -1008,66 +1055,35 @@ static int select_task_rq_fair(struct task_struct *p, int sync)
         /*
          * Check for affine wakeup and passive balancing possibilities.
          */
-        if (this_sd) {
-                int idx = this_sd->wake_idx;
-                unsigned int imbalance;
-                unsigned long load, this_load;
-
-                imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
-
-                load = source_load(cpu, idx);
-                this_load = target_load(this_cpu, idx);
-
-                new_cpu = this_cpu; /* Wake to this CPU if we can */
-
-                if (this_sd->flags & SD_WAKE_AFFINE) {
-                        unsigned long tl = this_load;
-                        unsigned long tl_per_task;
-
-                        /*
-                         * Attract cache-cold tasks on sync wakeups:
-                         */
-                        if (sync && !task_hot(p, rq->clock, this_sd))
-                                goto out_set_cpu;
-
-                        schedstat_inc(p, se.nr_wakeups_affine_attempts);
-                        tl_per_task = cpu_avg_load_per_task(this_cpu);
-
-                        /*
-                         * If sync wakeup then subtract the (maximum possible)
-                         * effect of the currently running task from the load
-                         * of the current CPU:
-                         */
-                        if (sync)
-                                tl -= current->se.load.weight;
-
-                        if ((tl <= load &&
-                                tl + target_load(cpu, idx) <= tl_per_task) ||
-                               100*(tl + p->se.load.weight) <= imbalance*load) {
-                                /*
-                                 * This domain has SD_WAKE_AFFINE and
-                                 * p is cache cold in this domain, and
-                                 * there is no bad imbalance.
-                                 */
-                                schedstat_inc(this_sd, ttwu_move_affine);
-                                schedstat_inc(p, se.nr_wakeups_affine);
-                                goto out_set_cpu;
-                        }
-                }
+        if (!this_sd)
+                goto out_keep_cpu;
 
-                /*
-                 * Start passive balancing when half the imbalance_pct
-                 * limit is reached.
-                 */
-                if (this_sd->flags & SD_WAKE_BALANCE) {
-                        if (imbalance*this_load <= 100*load) {
-                                schedstat_inc(this_sd, ttwu_move_balance);
-                                schedstat_inc(p, se.nr_wakeups_passive);
-                                goto out_set_cpu;
-                        }
+        idx = this_sd->wake_idx;
+
+        imbalance = 100 + (this_sd->imbalance_pct - 100) / 2;
+
+        load = source_load(cpu, idx);
+        this_load = target_load(this_cpu, idx);
+
+        new_cpu = this_cpu; /* Wake to this CPU if we can */
+
+        if (wake_affine(rq, this_sd, p, cpu, this_cpu, sync, idx,
+                                     load, this_load, imbalance))
+                goto out_set_cpu;
+
+        /*
+         * Start passive balancing when half the imbalance_pct
+         * limit is reached.
+         */
+        if (this_sd->flags & SD_WAKE_BALANCE) {
+                if (imbalance*this_load <= 100*load) {
+                        schedstat_inc(this_sd, ttwu_move_balance);
+                        schedstat_inc(p, se.nr_wakeups_passive);
+                        goto out_set_cpu;
                 }
         }
 
+out_keep_cpu:
         new_cpu = cpu; /* Could not wake to this_cpu. Wake to cpu instead */
 out_set_cpu:
         return wake_idle(new_cpu, p);