[PATCH] DLS: add dl_time_equal helper in deadline scheduler

[PATCH] DLS: add dl_time_equal helper in deadline scheduler

[Hillf Danton]

Hi all

A tiny helper, dl_time_equal, is added for easing readers.

And dl_entity_preempt is redefined to be bool, and its comment is also changed.

Signed-off-by: Hillf Danton <dhillf@gmail.com>
---

--- a/kernel/sched_dl.c	Sat Apr  7 15:00:28 2012
+++ b/kernel/sched_dl.c	Sat Apr  7 15:20:10 2012
@@ -16,16 +16,21 @@
  */
 static const struct sched_class dl_sched_class;

-static inline int dl_time_before(u64 a, u64 b)
+static inline bool dl_time_equal(u64 a, u64 b)
+{
+	return a == b;
+}
+
+static inline bool dl_time_before(u64 a, u64 b)
 {
 	return (s64)(a - b) < 0;
 }

 /*
- * Tells if entity @a should preempt entity @b.
+ * Return true if entity @a could preempt entity @b in term of deadline
  */
-static inline
-int dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
+static inline bool
+dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
 {
 	return dl_time_before(a->deadline, b->deadline);
 }
@@ -885,7 +890,7 @@ static void check_preempt_curr_dl(struct
 	 * In the unlikely case current and p have the same deadline
 	 * let us try to decide what's the best thing to do...
 	 */
-	if ((s64)(p->dl.deadline - rq->curr->dl.deadline) == 0 &&
+	if (dl_time_equal(p->dl.deadline, rq->curr->dl.deadline) &&
 	    !need_resched())
 		check_preempt_equal_dl(rq, p);
 #endif /* CONFIG_SMP */
--

Re: [PATCH] DLS: add dl_time_equal helper in deadline scheduler

[Juri Lelli]

Hi,

On 04/07/2012 09:49 AM, Hillf Danton wrote:
> Hi all
>
> A tiny helper, dl_time_equal, is added for easing readers.
>
> And dl_entity_preempt is redefined to be bool, and its comment is also changed.
>
> Signed-off-by: Hillf Danton<dhillf@gmail.com>
> ---
>
> --- a/kernel/sched_dl.c	Sat Apr  7 15:00:28 2012
> +++ b/kernel/sched_dl.c	Sat Apr  7 15:20:10 2012
> @@ -16,16 +16,21 @@
>    */
>   static const struct sched_class dl_sched_class;
>
> -static inline int dl_time_before(u64 a, u64 b)
> +static inline bool dl_time_equal(u64 a, u64 b)
> +{
> +	return a == b;
> +}
> +
> +static inline bool dl_time_before(u64 a, u64 b)
>   {
>   	return (s64)(a - b)<  0;
>   }
>
>   /*
> - * Tells if entity @a should preempt entity @b.
> + * Return true if entity @a could preempt entity @b in term of deadline
>    */
> -static inline
> -int dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
> +static inline bool
> +dl_entity_preempt(struct sched_dl_entity *a, struct sched_dl_entity *b)
>   {
>   	return dl_time_before(a->deadline, b->deadline);
>   }
> @@ -885,7 +890,7 @@ static void check_preempt_curr_dl(struct
>   	 * In the unlikely case current and p have the same deadline
>   	 * let us try to decide what's the best thing to do...
>   	 */
> -	if ((s64)(p->dl.deadline - rq->curr->dl.deadline) == 0&&
> +	if (dl_time_equal(p->dl.deadline, rq->curr->dl.deadline)&&
>   	!need_resched())
>   		check_preempt_equal_dl(rq, p);
>   #endif /* CONFIG_SMP */
> --

I'll change the comparison to be deadline_a == deadline_b, but I don't see the
need for a special helper function. It is used only once, better to have the
comparison really inline (a very special case).

Thanks and Regards,

- Juri

Re: [PATCH] DLS: add dl_time_equal helper in deadline scheduler

[Hillf Danton]

On Mon, Apr 9, 2012 at 3:34 PM, Juri Lelli <juri.lelli@gmail.com> wrote:
>
> I'll change the comparison to be deadline_a == deadline_b
>
Good and fair.
-hd