From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH 0/3] KVM-userspace: add NUMA support for guests Date: Fri, 28 Nov 2008 09:14:29 +0100 Message-ID: <87fxlcxo62.fsf@basil.nowhere.org> References: <492F1DD9.8030901@amd.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , kvm@vger.kernel.org To: Andre Przywara Return-path: Received: from one.firstfloor.org ([213.235.205.2]:44709 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750811AbYK1IO2 (ORCPT ); Fri, 28 Nov 2008 03:14:28 -0500 In-Reply-To: <492F1DD9.8030901@amd.com> (Andre Przywara's message of "Thu, 27 Nov 2008 23:23:21 +0100") Sender: kvm-owner@vger.kernel.org List-ID: Andre Przywara writes: > It also improves the one node case by pinning a guest to this node and > avoiding access of remote memory from one VCPU. It depends -- it's not necessarily an improvement. e.g. if it leads to some CPUs being idle while others are oversubscribed because of the pinning you typically lose more than you win. In general default pinning is a bad idea in my experience. Alternative more flexible strategies: - Do a mapping from CPU to node at runtime by using getcpu() - Migrate to complete nodes using migrate_pages when qemu detects node migration on the host. -Andi -- ak@linux.intel.com