linux-kernel - [PATCH] numa,sched: fix load_to

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Date:	Sun, 8 Jun 2014 16:55:57 -0400
From:	Rik van Riel <riel@...hat.com>
To:	linux-kernel@...r.kernel.org
Cc:	peterz@...radead.org, mgorman@...e.de, mingo@...nel.org,
	torvalds@...ux-foundation.org
Subject: [PATCH] numa,sched: fix load_to_imbalanced logic inversion

This function is supposed to return true if the new load imbalance
is worse than the old one. It didn't. I can only hope brown paper
bags are in style.

Now things converge much better on both the 4 node and 8 node systems.

I am not sure why this did not seem to impact specjbb performance on
the 4 node system, which is the system I have full-time access to.

This bug was introduced recently, with commit e63da036

Signed-off-by: Rik van Riel <riel@...hat.com>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 6a90f67..7fb3e47 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -1112,7 +1112,7 @@ static bool load_too_imbalanced(long orig_src_load, long orig_dst_load,
 	old_imb = orig_dst_load * 100 - orig_src_load * env->imbalance_pct;
 
 	/* Would this change make things worse? */
-	return (old_imb > imb);
+	return (imb > old_imb);
 }
 
 /*

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