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Subject[RFC PATCH 2/4] SCHED_DEADLINE cpu heap code clarification/refactory.
Date
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@infradead.org>
Cc: Juri Lelli <juri.lelli@arm.com>
Cc: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.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
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