linux-kernel - [RFC PATCH 16/16] sched: Debug bits...

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Message-Id: <20543884f2f97fe59b5d0900734b424f08145d56.1593530334.git.vpillai@digitalocean.com>
Date:   Tue, 30 Jun 2020 21:32:37 +0000
From:   Vineeth Remanan Pillai <vpillai@...italocean.com>
To:     Nishanth Aravamudan <naravamudan@...italocean.com>,
        Julien Desfossez <jdesfossez@...italocean.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Tim Chen <tim.c.chen@...ux.intel.com>, mingo@...nel.org,
        tglx@...utronix.de, pjt@...gle.com, torvalds@...ux-foundation.org
Cc:     linux-kernel@...r.kernel.org, subhra.mazumdar@...cle.com,
        fweisbec@...il.com, keescook@...omium.org, kerrnel@...gle.com,
        Phil Auld <pauld@...hat.com>, Aaron Lu <aaron.lwe@...il.com>,
        Aubrey Li <aubrey.intel@...il.com>,
        Valentin Schneider <valentin.schneider@....com>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Joel Fernandes <joelaf@...gle.com>, joel@...lfernandes.org,
        vineethrp@...il.com, Chen Yu <yu.c.chen@...el.com>,
        Christian Brauner <christian.brauner@...ntu.com>
Subject: [RFC PATCH 16/16] sched: Debug bits...

From: Peter Zijlstra <peterz@...radead.org>

Not-Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.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 2ec56970d6bb..0362102fa3d2 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -105,6 +105,10 @@ 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;
 
@@ -302,12 +306,16 @@ 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)
@@ -4477,6 +4485,14 @@ 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;
 	}
 
@@ -4551,6 +4567,9 @@ 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;
 			}
 
@@ -4559,6 +4578,9 @@ 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
@@ -4575,6 +4597,8 @@ 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)
@@ -4602,6 +4626,7 @@ 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
@@ -4624,11 +4649,20 @@ 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:
@@ -4667,6 +4701,10 @@ 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);
@@ -7305,6 +7343,8 @@ 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