1 files changed, 76 insertions, 10 deletions

diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c
index 517f72b008f5..a57fd8f27498 100644
--- a/kernel/sched/core_sched.c
+++ b/kernel/sched/core_sched.c
@@ -1,8 +1,5 @@
 // SPDX-License-Identifier: GPL-2.0-only
 
-#include <linux/prctl.h>
-#include "sched.h"
-
 /*
  * A simple wrapper around refcount. An allocated sched_core_cookie's
  * address is used to compute the cookie of the task.
@@ -59,7 +56,6 @@ static unsigned long sched_core_update_cookie(struct task_struct *p,
 	unsigned long old_cookie;
 	struct rq_flags rf;
 	struct rq *rq;
-	bool enqueued;
 
 	rq = task_rq_lock(p, &rf);
 
@@ -71,22 +67,28 @@ static unsigned long sched_core_update_cookie(struct task_struct *p,
 	 */
 	SCHED_WARN_ON((p->core_cookie || cookie) && !sched_core_enabled(rq));
 
-	enqueued = sched_core_enqueued(p);
-	if (enqueued)
-		sched_core_dequeue(rq, p);
+	if (sched_core_enqueued(p))
+		sched_core_dequeue(rq, p, DEQUEUE_SAVE);
 
 	old_cookie = p->core_cookie;
 	p->core_cookie = cookie;
 
-	if (enqueued)
+	/*
+	 * Consider the cases: !prev_cookie and !cookie.
+	 */
+	if (cookie && task_on_rq_queued(p))
 		sched_core_enqueue(rq, p);
 
 	/*
 	 * If task is currently running, it may not be compatible anymore after
 	 * the cookie change, so enter the scheduler on its CPU to schedule it
 	 * away.
+	 *
+	 * Note that it is possible that as a result of this cookie change, the
+	 * core has now entered/left forced idle state. Defer accounting to the
+	 * next scheduling edge, rather than always forcing a reschedule here.
 	 */
-	if (task_running(rq, p))
+	if (task_on_cpu(rq, p))
 		resched_curr(rq);
 
 	task_rq_unlock(rq, p, &rf);
@@ -203,7 +205,7 @@ int sched_core_share_pid(unsigned int cmd, pid_t pid, enum pid_type type,
 	default:
 		err = -EINVAL;
 		goto out;
-	};
+	}
 
 	if (type == PIDTYPE_PID) {
 		__sched_core_set(task, cookie);
@@ -232,3 +234,67 @@ out:
 	return err;
 }
 
+#ifdef CONFIG_SCHEDSTATS
+
+/* REQUIRES: rq->core's clock recently updated. */
+void __sched_core_account_forceidle(struct rq *rq)
+{
+	const struct cpumask *smt_mask = cpu_smt_mask(cpu_of(rq));
+	u64 delta, now = rq_clock(rq->core);
+	struct rq *rq_i;
+	struct task_struct *p;
+	int i;
+
+	lockdep_assert_rq_held(rq);
+
+	WARN_ON_ONCE(!rq->core->core_forceidle_count);
+
+	if (rq->core->core_forceidle_start == 0)
+		return;
+
+	delta = now - rq->core->core_forceidle_start;
+	if (unlikely((s64)delta <= 0))
+		return;
+
+	rq->core->core_forceidle_start = now;
+
+	if (WARN_ON_ONCE(!rq->core->core_forceidle_occupation)) {
+		/* can't be forced idle without a running task */
+	} else if (rq->core->core_forceidle_count > 1 ||
+		   rq->core->core_forceidle_occupation > 1) {
+		/*
+		 * For larger SMT configurations, we need to scale the charged
+		 * forced idle amount since there can be more than one forced
+		 * idle sibling and more than one running cookied task.
+		 */
+		delta *= rq->core->core_forceidle_count;
+		delta = div_u64(delta, rq->core->core_forceidle_occupation);
+	}
+
+	for_each_cpu(i, smt_mask) {
+		rq_i = cpu_rq(i);
+		p = rq_i->core_pick ?: rq_i->curr;
+
+		if (p == rq_i->idle)
+			continue;
+
+		/*
+		 * Note: this will account forceidle to the current cpu, even
+		 * if it comes from our SMT sibling.
+		 */
+		__account_forceidle_time(p, delta);
+	}
+}
+
+void __sched_core_tick(struct rq *rq)
+{
+	if (!rq->core->core_forceidle_count)
+		return;
+
+	if (rq != rq->core)
+		update_rq_clock(rq->core);
+
+	__sched_core_account_forceidle(rq);
+}
+
+#endif /* CONFIG_SCHEDSTATS */