This is a note to let you know that I've just added the patch titled
powerpc: fix numa distance for form0 device tree
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
powerpc-fix-numa-distance-for-form0-device-tree.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 7122beeee7bc1757682049780179d7c216dd1c83 Mon Sep 17 00:00:00 2001
From: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
Date: Fri, 22 Mar 2013 05:49:35 +0000
Subject: powerpc: fix numa distance for form0 device tree
From: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
commit 7122beeee7bc1757682049780179d7c216dd1c83 upstream.
The following commit breaks numa distance setup for old powerpc
systems that use form0 encoding in device tree.
commit 41eab6f88f24124df89e38067b3766b7bef06ddb
powerpc/numa: Use form 1 affinity to setup node distance
Device tree node /rtas/ibm,associativity-reference-points would
index into /cpus/PowerPCxxxx/ibm,associativity based on form0 or
form1 encoding detected by ibm,architecture-vec-5 property.
All modern systems use form1 and current kernel code is correct.
However, on older systems with form0 encoding, the numa distance
will get hard coded as LOCAL_DISTANCE for all nodes. This causes
task scheduling anomaly since scheduler will skip building numa
level domain (topmost domain with all cpus) if all numa distances
are same. (value of 'level' in sched_init_numa() will remain 0)
Prior to the above commit:
((from) == (to) ? LOCAL_DISTANCE : REMOTE_DISTANCE)
Restoring compatible behavior with this patch for old powerpc systems
with device tree where numa distance are encoded as form0.
Signed-off-by: Vaidyanathan Srinivasan <svaidy@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Michael Ellerman <michael@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/mm/numa.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -201,7 +201,7 @@ int __node_distance(int a, int b)
int distance = LOCAL_DISTANCE;
if (!form1_affinity)
- return distance;
+ return ((a == b) ? LOCAL_DISTANCE : REMOTE_DISTANCE);
for (i = 0; i < distance_ref_points_depth; i++) {
if (distance_lookup_table[a][i] == distance_lookup_table[b][i])
Patches currently in stable-queue which might be from svaidy@xxxxxxxxxxxxxxxxxx are
queue-3.4/powerpc-fix-numa-distance-for-form0-device-tree.patch
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