Revert "sched/fair: Introduce SIS_CURRENT to wake up short task on cu…

…rrent CPU"

This reverts commit 3a096df.

kernel/sched/fair.c

@@ -6397,46 +6397,6 @@ static int wake_wide(struct task_struct *p)
 	return 1;
 }
 
-/*
- * Wake up the task on current CPU, if the following conditions are met:
- *
- * 1. waker A is the only running task on this_cpu
- * 3. A is a short duration task (waker will fall asleep soon)
- * 4. wakee B is a short duration task (impact of B on A is minor)
- * 5. A and B wake up each other alternately
- */
-static bool
-wake_on_current(int this_cpu, struct task_struct *p)
-{
-	if (!sched_feat(SIS_CURRENT))
-		return false;
-
-	if (cpu_rq(this_cpu)->nr_running > 1)
-		return false;
-
-	/*
-	 * If a task switches in and then voluntarily relinquishes the
-	 * CPU quickly, it is regarded as a short duration task. In that
-	 * way, the short waker is likely to relinquish the CPU soon, which
-	 * provides room for the wakee. Meanwhile, a short wakee would bring
-	 * minor impact to the target rq. Put the short waker and wakee together
-	 * bring benefit to cache-share task pairs and avoid migration overhead.
-	 */
-	if (!current->se.dur_avg || ((current->se.dur_avg * 8) >= sysctl_sched_min_granularity))
-		return false;
-
-	if (!p->se.dur_avg || ((p->se.dur_avg * 8) >= sysctl_sched_min_granularity))
-		return false;
-
-	if (current->wakee_flips || p->wakee_flips)
-		return false;
-
-	if (current->last_wakee != p || p->last_wakee != current)
-		return false;
-
-	return true;
-}
-
 /*
  * The purpose of wake_affine() is to quickly determine on which CPU we can run
  * soonest. For the purpose of speed we only consider the waking and previous
@@ -6530,9 +6490,6 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p,
 	if (sched_feat(WA_WEIGHT) && target == nr_cpumask_bits)
 		target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
 
-	if (target == nr_cpumask_bits && wake_on_current(this_cpu, p))
-		target = this_cpu;
-
 	schedstat_inc(p->stats.nr_wakeups_affine_attempts);
 	if (target == nr_cpumask_bits)
 		return prev_cpu;
@@ -7033,9 +6990,6 @@ static int select_idle_sibling(struct task_struct *p, int prev, int target)
 		}
 	}
 
-	if (smp_processor_id() == target && wake_on_current(target, p))
-		return target;
-
 	i = select_idle_cpu(p, sd, has_idle_core, target);
 	if ((unsigned)i < nr_cpumask_bits)
 		return i;

kernel/sched/features.h

@@ -62,7 +62,6 @@ SCHED_FEAT(TTWU_QUEUE, true)
  */
 SCHED_FEAT(SIS_PROP, false)
 SCHED_FEAT(SIS_UTIL, true)
-SCHED_FEAT(SIS_CURRENT, true)
 
 /*
  * Issue a WARN when we do multiple update_rq_clock() calls