[PATCH] sched,fair: Remove > u32 weight handling for delta

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From	Afzal Mohammed <afzal.mohd.ma@gmail.com>
Newsgroups	linux.kernel
Subject	[PATCH] sched,fair: Remove > u32 weight handling for delta
Date	Mon, 06 Jul 2015 04:50:01 +0200
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scaled down weight 'fact' would not be > u32 rather than unlikely as the
values being passed for delta is either NICE_O_LOAD or the weight of the
'se' which would be a value that can be accomodated in a u32. Remove the
initial > u32 handling on 'fact'.

9dbdb15553239 ("sched/fair: Rework sched_fair time accounting") in
addition to fixing the original issue of time moving backwards elsewhere
in the code, handled delta > u32 case (due to NO_HZ_FULL) which brought
in as it's part the change changed here. The hunk being removed here
would not make a difference to it as this is on scaled weight > u32.
And pre-"9dbdb15553239" doesn't seem to have logical equivalent of hunk
removed here either.

Signed-off-by: Afzal Mohammed <afzal.mohd.ma@gmail.com>
---
    
System here (that mainly does kernel build) has been running with this
change for last couple of weeks without any issue observed.
    
 kernel/sched/fair.c | 7 -------
 1 file changed, 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3d57cc0ca0a6..0cc58a7bdd16 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -218,13 +218,6 @@ static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight
 
 	__update_inv_weight(lw);
 
-	if (unlikely(fact >> 32)) {
-		while (fact >> 32) {
-			fact >>= 1;
-			shift--;
-		}
-	}
-
 	/* hint to use a 32x32->64 mul */
 	fact = (u64)(u32)fact * lw->inv_weight;
 
-- 
2.1.4

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[PATCH] sched,fair: Remove > u32 weight handling for delta Afzal Mohammed <afzal.mohd.ma@gmail.com> - 2015-07-06 04:50 +0200

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