Re: [patch] CFS scheduler, -v8

[Ingo Molnar <mingo@elte.hu>]

* Willy Tarreau <w@1wt.eu> wrote:

> Just a hint: while your code here is correct, it is a good practise to 
> check against < 0 instead, so that if for any reason you sometimes 
> forget to cast to signed, the compiler will emit a warning stating 
> that the condition is always false. This would simply become :
> 
> -		if (key < entry->fair_key) {
> +		if ((s64)(key - entry->fair_key) < 0) {

done :-) (Btw., the key is still s64 so the cast is technically 
unnecessary - but now the code would be correct with the key being u64 
too.)

	Ingo

Index: linux/kernel/sched_fair.c
===================================================================
--- linux.orig/kernel/sched_fair.c
+++ linux/kernel/sched_fair.c
@@ -60,7 +60,7 @@ static inline void __enqueue_task_fair(s
 		 * We dont care about collisions. Nodes with
 		 * the same key stay together.
 		 */
-		if (key < entry->fair_key) {
+		if ((s64)(key - entry->fair_key) < 0) {
 			link = &parent->rb_left;
 		} else {
 			link = &parent->rb_right;