[RFC PATCH 13/13] sched: Debug bits...

[vpillai <vpillai@digitalocean.com>]

From: Peter Zijlstra <peterz@infradead.org>

Not-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/core.c | 44 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 11e5a2a494ac..a01df3e0b11e 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -110,6 +110,10 @@ static inline bool prio_less(struct task_struct *a, struct task_struct *b)
 
 	int pa = __task_prio(a), pb = __task_prio(b);
 
+	trace_printk("(%s/%d;%d,%Lu,%Lu) ?< (%s/%d;%d,%Lu,%Lu)\n",
+		     a->comm, a->pid, pa, a->se.vruntime, a->dl.deadline,
+		     b->comm, b->pid, pb, b->se.vruntime, b->dl.deadline);
+
 	if (-pa < -pb)
 		return true;
 
@@ -315,12 +319,16 @@ static void __sched_core_enable(void)
 
 	static_branch_enable(&__sched_core_enabled);
 	stop_machine(__sched_core_stopper, (void *)true, NULL);
+
+	printk("core sched enabled\n");
 }
 
 static void __sched_core_disable(void)
 {
 	stop_machine(__sched_core_stopper, (void *)false, NULL);
 	static_branch_disable(&__sched_core_enabled);
+
+	printk("core sched disabled\n");
 }
 
 void sched_core_get(void)
@@ -4460,6 +4468,14 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 			put_prev_task(rq, prev);
 			set_next_task(rq, next);
 		}
+
+		trace_printk("pick pre selected (%u %u %u): %s/%d %lx\n",
+			     rq->core->core_task_seq,
+			     rq->core->core_pick_seq,
+			     rq->core_sched_seq,
+			     next->comm, next->pid,
+			     next->core_cookie);
+
 		return next;
 	}
 
@@ -4540,6 +4556,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 			 */
 			if (i == cpu && !need_sync && !p->core_cookie) {
 				next = p;
+				trace_printk("unconstrained pick: %s/%d %lx\n",
+					     next->comm, next->pid, next->core_cookie);
+
 				goto done;
 			}
 
@@ -4548,6 +4567,9 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 
 			rq_i->core_pick = p;
 
+			trace_printk("cpu(%d): selected: %s/%d %lx\n",
+				     i, p->comm, p->pid, p->core_cookie);
+
 			/*
 			 * If this new candidate is of higher priority than the
 			 * previous; and they're incompatible; we need to wipe
@@ -4564,6 +4586,8 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 				rq->core->core_cookie = p->core_cookie;
 				max = p;
 
+				trace_printk("max: %s/%d %lx\n", max->comm, max->pid, max->core_cookie);
+
 				if (old_max) {
 					for_each_cpu(j, smt_mask) {
 						if (j == i)
@@ -4591,6 +4615,7 @@ next_class:;
 	rq->core->core_pick_seq = rq->core->core_task_seq;
 	next = rq->core_pick;
 	rq->core_sched_seq = rq->core->core_pick_seq;
+	trace_printk("picked: %s/%d %lx\n", next->comm, next->pid, next->core_cookie);
 
 	/*
 	 * Reschedule siblings
@@ -4616,11 +4641,20 @@ next_class:;
 		if (i == cpu)
 			continue;
 
-		if (rq_i->curr != rq_i->core_pick)
+		if (rq_i->curr != rq_i->core_pick) {
+			trace_printk("IPI(%d)\n", i);
 			resched_curr(rq_i);
+		}
 
 		/* Did we break L1TF mitigation requirements? */
-		WARN_ON_ONCE(!cookie_match(next, rq_i->core_pick));
+		if (unlikely(!cookie_match(next, rq_i->core_pick))) {
+			trace_printk("[%d]: cookie mismatch. %s/%d/0x%lx/0x%lx\n",
+				     rq_i->cpu, rq_i->core_pick->comm,
+				     rq_i->core_pick->pid,
+				     rq_i->core_pick->core_cookie,
+				     rq_i->core->core_cookie);
+			WARN_ON_ONCE(1);
+		}
 	}
 
 done:
@@ -4659,6 +4693,10 @@ static bool try_steal_cookie(int this, int that)
 		if (p->core_occupation > dst->idle->core_occupation)
 			goto next;
 
+		trace_printk("core fill: %s/%d (%d->%d) %d %d %lx\n",
+			     p->comm, p->pid, that, this,
+			     p->core_occupation, dst->idle->core_occupation, cookie);
+
 		p->on_rq = TASK_ON_RQ_MIGRATING;
 		deactivate_task(src, p, 0);
 		set_task_cpu(p, this);
@@ -7287,6 +7325,8 @@ int sched_cpu_starting(unsigned int cpu)
 		WARN_ON_ONCE(rq->core && rq->core != core_rq);
 		rq->core = core_rq;
 	}
+
+	printk("core: %d -> %d\n", cpu, cpu_of(core_rq));
 #endif /* CONFIG_SCHED_CORE */
 
 	sched_rq_cpu_starting(cpu);
-- 
2.17.1