linux-kernel - [PATCH 4/4] sched/stats: branch statistics for pick

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Date:   Tue,  7 Nov 2023 17:05:10 +0800
From:   Abel Wu <wuyun.abel@...edance.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Valentin Schneider <valentin.schneider@....com>
Cc:     Barry Song <21cnbao@...il.com>,
        Benjamin Segall <bsegall@...gle.com>,
        Chen Yu <yu.c.chen@...el.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        "Gautham R . Shenoy" <gautham.shenoy@....com>,
        Joel Fernandes <joel@...lfernandes.org>,
        K Prateek Nayak <kprateek.nayak@....com>,
        Mike Galbraith <efault@....de>,
        Qais Yousef <qyousef@...alina.io>,
        Tim Chen <tim.c.chen@...ux.intel.com>,
        Yicong Yang <yangyicong@...wei.com>,
        Youssef Esmat <youssefesmat@...omium.org>,
        linux-kernel@...r.kernel.org, Abel Wu <wuyun.abel@...edance.com>
Subject: [PATCH 4/4] sched/stats: branch statistics for pick_eevdf

For trace purpose only, not intended for upstream.

Signed-off-by: Abel Wu <wuyun.abel@...edance.com>
---
 kernel/sched/fair.c  | 12 ++++++++++--
 kernel/sched/sched.h |  5 +++++
 kernel/sched/stats.c |  6 ++++--
 3 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index a1fdd0c7a051..9b07e9437526 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -899,13 +899,16 @@ static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq)
 	struct sched_entity *se = __pick_first_entity(cfs_rq);
 	struct sched_entity *curr = cfs_rq->curr;
 	struct sched_entity *best = NULL;
+	struct rq *rq = rq_of(cfs_rq);
 
 	/*
 	 * We can safely skip eligibility check if there is only one entity
 	 * in this cfs_rq, saving some cycles.
 	 */
-	if (cfs_rq->nr_running == 1)
+	if (cfs_rq->nr_running == 1) {
+		schedstat_inc(rq->pick_direct);
 		return curr && curr->on_rq ? curr : se;
+	}
 
 	if (curr && (!curr->on_rq || !entity_eligible(cfs_rq, curr)))
 		curr = NULL;
@@ -914,15 +917,20 @@ static struct sched_entity *pick_eevdf(struct cfs_rq *cfs_rq)
 	 * Once selected, run a task until it either becomes non-eligible or
 	 * until it gets a new slice. See the HACK in set_next_entity().
 	 */
-	if (sched_feat(RUN_TO_PARITY) && curr && curr->vlag == curr->deadline)
+	if (sched_feat(RUN_TO_PARITY) && curr && curr->vlag == curr->deadline) {
+		schedstat_inc(rq->pick_parity);
 		return curr;
+	}
 
 	/* Pick the leftmost entity if it's eligible */
 	if (se && entity_eligible(cfs_rq, se)) {
+		schedstat_inc(rq->pick_fast);
 		best = se;
 		goto found;
 	}
 
+	schedstat_inc(rq->pick_slow);
+
 	/* Heap search for the EEVD entity */
 	while (node) {
 		struct rb_node *left = node->rb_left;
diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h
index 539c7e763f15..85a79990a698 100644
--- a/kernel/sched/sched.h
+++ b/kernel/sched/sched.h
@@ -1105,6 +1105,11 @@ struct rq {
 	/* try_to_wake_up() stats */
 	unsigned int		ttwu_count;
 	unsigned int		ttwu_local;
+
+	unsigned int		pick_direct;
+	unsigned int		pick_parity;
+	unsigned int		pick_fast;
+	unsigned int		pick_slow;
 #endif
 
 #ifdef CONFIG_CPU_IDLE
diff --git a/kernel/sched/stats.c b/kernel/sched/stats.c
index 857f837f52cb..4b862c798989 100644
--- a/kernel/sched/stats.c
+++ b/kernel/sched/stats.c
@@ -133,12 +133,14 @@ static int show_schedstat(struct seq_file *seq, void *v)
 
 		/* runqueue-specific stats */
 		seq_printf(seq,
-		    "cpu%d %u 0 %u %u %u %u %llu %llu %lu",
+		    "cpu%d %u 0 %u %u %u %u %llu %llu %lu %u %u %u %u",
 		    cpu, rq->yld_count,
 		    rq->sched_count, rq->sched_goidle,
 		    rq->ttwu_count, rq->ttwu_local,
 		    rq->rq_cpu_time,
-		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount);
+		    rq->rq_sched_info.run_delay, rq->rq_sched_info.pcount,
+		    rq->pick_direct, rq->pick_parity,
+		    rq->pick_fast, rq->pick_slow);
 
 		seq_printf(seq, "\n");
 
-- 
2.37.3