[PATCH 2/2] sched: fair: fix calc_delta_asym

[Peter Zijlstra]

The goal of calc_delta_asym() is to be asymetrically around NICE_0_LOAD, in
that it favours >=0 over <0. The current implementation does not achieve that.

 -20         |
             |
   0 --------+-------
           .'
  19     .'

Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
---
 kernel/sched_fair.c |   13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

Index: linux-2.6/kernel/sched_fair.c
===================================================================
--- linux-2.6.orig/kernel/sched_fair.c
+++ linux-2.6/kernel/sched_fair.c
@@ -417,12 +417,17 @@ calc_delta_fair(unsigned long delta, str
 static inline unsigned long
 calc_delta_asym(unsigned long delta, struct sched_entity *se)
 {
-	unsigned long fair = calc_delta_fair(delta, se);
+	if (se->load.weight < NICE_0_LOAD) {
+		struct load_weight lw = {
+			.weight = NICE_0_LOAD,
+			.inv_weight = 1UL << (WMULT_SHIFT-NICE_0_SHIFT)
+		};
 
-	if (fair > delta)
-		fair = delta;
+		delta = calc_delta_mine(delta, cfs_rq_of(se)->load.weight, &lw);
+		se = parent_entity(se);
+	}
 
-	return fair;
+	return calc_delta_fair(delta, se);
 }
 
 /*

--

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