linux-kernel - [RFC 33/60] cosched: Allow resched_curr() to be called for hierarchical runqueues

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Message-Id: <20180907214047.26914-34-jschoenh@amazon.de>
Date:   Fri,  7 Sep 2018 23:40:20 +0200
From:   Jan H. Schönherr <jschoenh@...zon.de>
To:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     Jan H. Schönherr <jschoenh@...zon.de>,
        linux-kernel@...r.kernel.org
Subject: [RFC 33/60] cosched: Allow resched_curr() to be called for hierarchical runqueues

The function resched_curr() kicks the scheduler for a certain runqueue,
assuming that the runqueue is already locked.

If called for a hierarchical runqueue, the equivalent operation is to
kick the leader. Unfortunately, we don't know whether we also hold
the CPU runqueue lock at this point, which is needed for resched_curr()
to work. Therefore, fall back to resched_cpu_locked() on higher levels.

Signed-off-by: Jan H. Schönherr <jschoenh@...zon.de>
---
 kernel/sched/core.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 337bae6fa836..c4358396f588 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -457,6 +457,11 @@ void resched_curr(struct rq *rq)
 
 	lockdep_assert_held(&rq->lock);
 
+#ifdef CONFIG_COSCHEDULING
+	if (rq->sdrq_data.level)
+		return resched_cpu_locked(rq->sdrq_data.leader);
+#endif
+
 	if (test_tsk_need_resched(curr))
 		return;
 
-- 
2.9.3.1.gcba166c.dirty