Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755920AbZIBGhM (ORCPT ); Wed, 2 Sep 2009 02:37:12 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755909AbZIBGhL (ORCPT ); Wed, 2 Sep 2009 02:37:11 -0400 Received: from smtp-out.google.com ([216.239.33.17]:37767 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755901AbZIBGhK (ORCPT ); Wed, 2 Sep 2009 02:37:10 -0400 DomainKey-Signature: a=rsa-sha1; s=beta; d=google.com; c=nofws; q=dns; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id: references:user-agent:mime-version:content-type:x-system-of-record; b=n/s5g5qNHUiG4iEvW6UsAtrdYmlBwDOpXx5yJaqmX14AQ0hfGfvdqxGMQNIfGIv2E kAlak3OUcWxUrk/RF8QzQ== Date: Tue, 1 Sep 2009 23:37:05 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: Ankita Garg cc: LKML , linuxppc-dev@ozlabs.org, Benjamin Herrenschmidt , Balbir Singh , Vaidyanathan Srinivasan Subject: Re: [PATCH v2] Fix fake numa on ppc In-Reply-To: <20090902060911.GA5728@in.ibm.com> Message-ID: References: <20090902060911.GA5728@in.ibm.com> User-Agent: Alpine 1.00 (DEB 882 2007-12-20) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1870 Lines: 54 On Wed, 2 Sep 2009, Ankita Garg wrote: > Hi, > > Below is a patch to fix a couple of issues with fake numa node creation > on ppc: > > 1) Presently, fake nodes could be created such that real numa node > boundaries are not respected. So a node could have lmbs that belong to > different real nodes. > On x86_64, we can use numa=off to completely disable NUMA so that all memory and all cpus are mapped to a single node 0. That's an extreme example of the above and is totally permissible. > 2) The cpu association is broken. On a JS22 blade for example, which is > a 2-node numa machine, I get the following: > > # cat /proc/cmdline > root=/dev/sda6 numa=fake=2G,4G,,6G,8G,10G,12G,14G,16G > # cat /sys/devices/system/node/node0/cpulist > 0-3 > # cat /sys/devices/system/node/node1/cpulist > 4-7 > # cat /sys/devices/system/node/node4/cpulist > > # > This doesn't show what the true NUMA topology of the machine is, could you please post the output of $ cat /sys/devices/system/node/node*/cpulist $ cat /sys/devices/system/node/node*/distance $ ls -d /sys/devices/system/node/node*/cpu[0-8] from a normal boot without any numa=fake? > So, though the cpus 4-7 should have been associated with node4, they > still belong to node1. The patch works by recording a real numa node > boundary and incrementing the fake node count. At the same time, a > mapping is stored from the real numa node to the first fake node that > gets created on it. > If there are multiple fake nodes on a real physical node, all cpus in that node should appear in the cpulist for each fake node for which it has local distance. -- 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/