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From:   "Joel Fernandes (Google)" <joel@joelfernandes.org>
To:     Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Peter Zijlstra <peterz@infradead.org>,
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        chris.hyser@oracle.com, Aubrey Li <aubrey.li@linux.intel.com>,
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        Tim Chen <tim.c.chen@intel.com>
Subject: [PATCH v8 -tip 26/26] sched: Debug bits...
Date:   Mon, 19 Oct 2020 21:43:36 -0400
Message-Id: <20201020014336.2076526-27-joel@joelfernandes.org>
In-Reply-To: <20201020014336.2076526-1-joel@joelfernandes.org>
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From: Peter Zijlstra <peterz@infradead.org>

Tested-by: Julien Desfossez <jdesfossez@digitalocean.com>
Not-Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
 kernel/sched/core.c | 37 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 211e0784675f..61758b5478d8 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -127,6 +127,10 @@ 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;
 
@@ -317,12 +321,16 @@ 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)
@@ -4978,6 +4986,13 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
 			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);
+
 		rq->core_pick = NULL;
 		return next;
 	}
@@ -5066,6 +5081,8 @@ 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;
 			}
 
@@ -5074,6 +5091,9 @@ 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
@@ -5090,6 +5110,8 @@ 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)
@@ -5120,6 +5142,7 @@ next_class:;
 
 	/* Something should have been selected for current CPU */
 	WARN_ON_ONCE(!next);
+	trace_printk("picked: %s/%d %lx\n", next->comm, next->pid, next->core_cookie);
 
 	/*
 	 * Reschedule siblings
@@ -5155,13 +5178,21 @@ next_class:;
 		}
 
 		/* 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);
+		}
 
 		if (rq_i->curr == rq_i->core_pick) {
 			rq_i->core_pick = NULL;
 			continue;
 		}
 
+		trace_printk("IPI(%d)\n", i);
 		resched_curr(rq_i);
 	}
 
@@ -5209,6 +5240,10 @@ 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);
-- 
2.29.0.rc1.297.gfa9743e501-goog