linux-kernel - [RFC PATCH 2/4] SCHED_DEADLINE cpu heap code clarification/refactory.

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Message-Id: <1468921493-10054-3-git-send-email-tommaso.cucinotta@sssup.it>
Date:	Tue, 19 Jul 2016 11:44:51 +0200
From:	Tommaso Cucinotta <tommaso.cucinotta@...up.it>
To:	Luca Abeni <luca.abeni@...tn.it>,
	Juri Lelli <juri.lelli@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>
Cc:	linux-kernel@...r.kernel.org, linux-dl@...is.sssup.it,
	Tommaso Cucinotta <tommaso.cucinotta@...up.it>,
	Juri Lelli <juri.lelli@....com>
Subject: [RFC PATCH 2/4] SCHED_DEADLINE cpu heap code clarification/refactory.

1. heapify up factored out in new dedicated function heapify_up()
   (avoids repeatition of same code)
2. call to cpudl_change_key() replaced with heapify_up() when
   cpudl_set actually inserts a new node in the heap

Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Juri Lelli <juri.lelli@....com>
Cc: Luca Abeni <luca.abeni@...tn.it>
Reviewed-by: Luca Abeni <luca.abeni@...tn.it>
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@...up.it>
---
 kernel/sched/cpudeadline.c | 38 +++++++++++++++++++-------------------
 1 file changed, 19 insertions(+), 19 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index d418449..3c42702 100644
--- a/kernel/sched/cpudeadline.c
+++ b/kernel/sched/cpudeadline.c
@@ -41,7 +41,7 @@ static void cpudl_exchange(struct cpudl *cp, int a, int b)
 	swap(cp->elements[cpu_a].idx, cp->elements[cpu_b].idx);
 }
 
-static void cpudl_heapify(struct cpudl *cp, int idx)
+static void cpudl_heapify_down(struct cpudl *cp, int idx)
 {
 	int l, r, largest;
 
@@ -66,20 +66,25 @@ static void cpudl_heapify(struct cpudl *cp, int idx)
 	}
 }
 
+static void cpudl_heapify_up(struct cpudl *cp, int idx)
+{
+	while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
+			cp->elements[idx].dl)) {
+		cpudl_exchange(cp, idx, parent(idx));
+		idx = parent(idx);
+	}
+}
+
 static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
 {
 	WARN_ON(idx == IDX_INVALID || !cpu_present(idx));
 
 	if (dl_time_before(new_dl, cp->elements[idx].dl)) {
 		cp->elements[idx].dl = new_dl;
-		cpudl_heapify(cp, idx);
+		cpudl_heapify_down(cp, idx);
 	} else {
 		cp->elements[idx].dl = new_dl;
-		while (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
-					cp->elements[idx].dl)) {
-			cpudl_exchange(cp, idx, parent(idx));
-			idx = parent(idx);
-		}
+		cpudl_heapify_up(cp, idx);
 	}
 }
 
@@ -154,24 +159,19 @@ void cpudl_set(struct cpudl *cp, int cpu, u64 dl, int is_valid)
 		cp->size--;
 		cp->elements[new_cpu].idx = old_idx;
 		cp->elements[cpu].idx = IDX_INVALID;
-		while (old_idx > 0 && dl_time_before(
-				cp->elements[parent(old_idx)].dl,
-				cp->elements[old_idx].dl)) {
-			cpudl_exchange(cp, old_idx, parent(old_idx));
-			old_idx = parent(old_idx);
-		}
+		cpudl_heapify_up(cp, old_idx);
 		cpumask_set_cpu(cpu, cp->free_cpus);
-                cpudl_heapify(cp, old_idx);
+                cpudl_heapify_down(cp, old_idx);
 
 		goto out;
 	}
 
 	if (old_idx == IDX_INVALID) {
-		cp->size++;
-		cp->elements[cp->size - 1].dl = dl;
-		cp->elements[cp->size - 1].cpu = cpu;
-		cp->elements[cpu].idx = cp->size - 1;
-		cpudl_change_key(cp, cp->size - 1, dl);
+		int size1 = cp->size++;
+		cp->elements[size1].dl = dl;
+		cp->elements[size1].cpu = cpu;
+		cp->elements[cpu].idx = size1;
+		cpudl_heapify_up(cp, size1);
 		cpumask_clear_cpu(cpu, cp->free_cpus);
 	} else {
 		cpudl_change_key(cp, old_idx, dl);
-- 
2.7.4