Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756128Ab2HTNyd (ORCPT ); Mon, 20 Aug 2012 09:54:33 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:33480 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755550Ab2HTNy2 (ORCPT ); Mon, 20 Aug 2012 09:54:28 -0400 Message-ID: <50324189.9040406@gmail.com> Date: Mon, 20 Aug 2012 21:54:17 +0800 From: Jianguo Wu User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:14.0) Gecko/20120713 Thunderbird/14.0 MIME-Version: 1.0 To: Wen Congyang CC: tony.luck@intel.com, fenghua.yu@intel.com, linux-ia64@vger.kernel.org, linux-kernel@vger.kernel.org, jiang.liu@huawei.com, guohanjun@huawei.com, qiuxishi@huawei.com, liuj97@gmail.com Subject: Re: [PATCH]mm/ia64: fix a node distance bug References: <5031D763.9010808@gmail.com> <5031E208.2080202@cn.fujitsu.com> In-Reply-To: <5031E208.2080202@cn.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2939 Lines: 90 On 2012/8/20 15:06, Wen Congyang wrote: > At 08/20/2012 02:21 PM, wujianguo Wrote: >> From: Jianguo Wu >> >> Hi all, >> When doing memory-hot-plug, We found node distance is wrong after offline >> a node in IA64 platform. For example system has 4 nodes: >> node distances: >> node 0 1 2 3 >> 0: 10 21 21 32 >> 1: 21 10 32 21 >> 2: 21 32 10 21 >> 3: 32 21 21 10 >> >> linux-drf:/sys/devices/system/node/node0 # cat distance >> 10 21 21 32 >> linux-drf:/sys/devices/system/node/node1 # cat distance >> 21 10 32 21 >> >> After offline node2: >> linux-drf:/sys/devices/system/node/node0 # cat distance >> 10 21 32 >> linux-drf:/sys/devices/system/node/node1 # cat distance >> 32 21 32 --------->expected value is: 21 10 21 >> >> In arch IA, we have following definition: >> extern u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES]; >> #define node_distance(from,to) (numa_slit[(from) * num_online_nodes() + (to)]) >> >> node distance is setup as following: >> acpi_numa_arch_fixup() >> { >> ... >> memset(numa_slit, -1, sizeof(numa_slit)); >> for (i = 0; i < slit_table->locality_count; i++) { >> if (!pxm_bit_test(i)) >> continue; >> node_from = pxm_to_node(i); >> for (j = 0; j < slit_table->locality_count; j++) { >> if (!pxm_bit_test(j)) >> continue; >> node_to = pxm_to_node(j); >> node_distance(node_from, node_to) = >> slit_table->entry[i * slit_table->locality_count + j]; >> } >> } >> ... >> } >> num_online_nodes() is a variable value, during system boot the return vale is 4, >> but after offline node2, the return value is 3, so we read a wrong node distance value. >> This patch is trying to fix this bug. >> >> Signed-off-by: Jianguo Wu >> --- >> arch/ia64/include/asm/numa.h | 2 +- >> 1 files changed, 1 insertions(+), 1 deletions(-) >> >> diff --git a/arch/ia64/include/asm/numa.h b/arch/ia64/include/asm/numa.h >> index 6a8a27c..2e27ef1 100644 >> --- a/arch/ia64/include/asm/numa.h >> +++ b/arch/ia64/include/asm/numa.h >> @@ -59,7 +59,7 @@ extern struct node_cpuid_s node_cpuid[NR_CPUS]; >> */ >> >> extern u8 numa_slit[MAX_NUMNODES * MAX_NUMNODES]; >> -#define node_distance(from,to) (numa_slit[(from) * num_online_nodes() + (to)]) >> +#define node_distance(from,to) (numa_slit[(from) * MAX_NUMNODES + (to)]) > > Hmm, MAX_NUMNODES is too large. I think num_possible_nodes() is better. > > Thanks > Wen Congyang > Hi Congyang, Thanks for you comments. numa_slit[MAX_NUMNODES * MAX_NUMNODES] is a static array, so I think it makes no difference using MAX_NUMNODES or num_online_nodes(). >> >> extern int paddr_to_nid(unsigned long paddr); >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/