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authorVaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>2013-03-22 05:49:35 +0000
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2013-05-11 13:38:00 -0700
commit5013bcf5cbd6969b8873b964e0d7aaab430cf643 (patch)
treef632e473aaa77772bcb57360d1033ebfc9c48350
parentbff066a411684d07e23307405f03cf7e7fc4afab (diff)
powerpc: fix numa distance for form0 device tree
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@linux.vnet.ibm.com> Signed-off-by: Michael Ellerman <michael@ellerman.id.au> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--arch/powerpc/mm/numa.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
index 2c1ae7a5fb5..97042c66e11 100644
--- a/arch/powerpc/mm/numa.c
+++ b/arch/powerpc/mm/numa.c
@@ -221,7 +221,7 @@ 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])