[tip:sched/core] sched/deadline: Refactor CPU heap code

tip-bot for Tommaso Cucinotta
2016-09-05T11:54:42Z

Commit-ID: 126b3b6842cc848fc9880e7816e0a8d743be51f1
Gitweb: http://git.kernel.org/tip/126b3b6842cc848fc9880e7816e0a8d743be51f1
Author: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
AuthorDate: Sun, 14 Aug 2016 16:27:06 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 5 Sep 2016 13:29:42 +0200

sched/deadline: Refactor CPU heap code

1. heapify up factored out in new dedicated function heapify_up()
(avoids repetition of same code)

2. call to cpudl_change_key() replaced with heapify_up() when
cpudl_set actually inserts a new node in the heap

3. cpudl_change_key() replaced with heapify() that heapifies up
or down as needed.

Signed-off-by: Tommaso Cucinotta <tommaso.cucinotta@sssup.it>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Luca Abeni <luca.abeni@unitn.it>
Reviewed-by: Juri Lelli <juri.lelli@arm.com>
Cc: Juri Lelli <juri.lelli@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-dl@retis.sssup.it
Link: http://lkml.kernel.org/r/1471184828-12644-2-git-send-email-tommaso.cucinotta@sssup.it
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
kernel/sched/cpudeadline.c | 50 +++++++++++++++++++++-------------------------
1 file changed, 23 insertions(+), 27 deletions(-)

diff --git a/kernel/sched/cpudeadline.c b/kernel/sched/cpudeadline.c
index d418449..0acb0d4 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;

@@ -66,23 +66,24 @@ static void cpudl_heapify(struct cpudl *cp, int idx)
}
}

-static void cpudl_change_key(struct cpudl *cp, int idx, u64 new_dl)
+static void cpudl_heapify_up(struct cpudl *cp, int idx)
{
- 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);
- } 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);
- }
+ 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_heapify(struct cpudl *cp, int idx)
+{
+ if (idx > 0 && dl_time_before(cp->elements[parent(idx)].dl,
+ cp->elements[idx].dl))
+ cpudl_heapify_up(cp, idx);
+ else
+ cpudl_heapify_down(cp, idx);
+}
+
static inline int cpudl_maximum(struct cpudl *cp)
{
return cp->elements[0].cpu;
@@ -154,27 +155,22 @@ 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(cp, old_idx);
cpumask_set_cpu(cpu, cp->free_cpus);
- cpudl_heapify(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 new_idx = cp->size++;
+ cp->elements[new_idx].dl = dl;
+ cp->elements[new_idx].cpu = cpu;
+ cp->elements[cpu].idx = new_idx;
+ cpudl_heapify_up(cp, new_idx);
cpumask_clear_cpu(cpu, cp->free_cpus);
} else {
- cpudl_change_key(cp, old_idx, dl);
+ cp->elements[old_idx].dl = dl;
+ cpudl_heapify(cp, old_idx);
}