From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e23smtp04.au.ibm.com (e23smtp04.au.ibm.com [202.81.31.146]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "e23smtp04.au.ibm.com", Issuer "GeoTrust SSL CA" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 2DE352C009E for ; Sat, 23 Mar 2013 02:49:51 +1100 (EST) Received: from /spool/local by e23smtp04.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Sat, 23 Mar 2013 01:39:21 +1000 Received: from d23relay05.au.ibm.com (d23relay05.au.ibm.com [9.190.235.152]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 62C8D2BB0023 for ; Sat, 23 Mar 2013 02:49:45 +1100 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay05.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r2MFadf65505500 for ; Sat, 23 Mar 2013 02:36:40 +1100 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r2MFnh15019607 for ; Sat, 23 Mar 2013 02:49:44 +1100 Date: Fri, 22 Mar 2013 21:19:35 +0530 From: Vaidyanathan Srinivasan To: Benjamin Herrenschmidt Subject: [BUG][PATCH] powerpc: fix numa distance for form0 device tree Message-ID: <20130322154935.GA26283@dirshya.in.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Cc: Linux PPC dev , Michael Neuling Reply-To: svaidy@linux.vnet.ibm.com List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , powerpc: fix numa distance for form0 device tree 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: #define node_distance(from,to) ((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 diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c index bba87ca..6a252c4 100644 --- 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])