Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757532AbcCCKxP (ORCPT ); Thu, 3 Mar 2016 05:53:15 -0500 Received: from mga09.intel.com ([134.134.136.24]:54299 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757450AbcCCKxJ (ORCPT ); Thu, 3 Mar 2016 05:53:09 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,532,1449561600"; d="scan'208";a="925913666" From: Liang Li To: mst@redhat.com, linux-kernel@vger.kernel.org Cc: akpm@linux-foundation.org, pbonzini@redhat.com, rth@twiddle.net, ehabkost@redhat.com, quintela@redhat.com, amit.shah@redhat.com, qemu-devel@nongnu.org, linux-mm@kvack.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, dgilbert@redhat.com, Liang Li Subject: [RFC kernel 0/2]A PV solution for KVM live migration optimization Date: Thu, 3 Mar 2016 18:46:57 +0800 Message-Id: <1457002019-15998-1-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2217 Lines: 60 The current QEMU live migration implementation mark the all the guest's RAM pages as dirtied in the ram bulk stage, all these pages will be processed and that takes quit a lot of CPU cycles. >From guest's point of view, it doesn't care about the content in free pages. We can make use of this fact and skip processing the free pages in the ram bulk stage, it can save a lot CPU cycles and reduce the network traffic significantly while speed up the live migration process obviously. This patch set is the kernel side implementation. It get the free pages information by traversing zone->free_area[order].free_list, and construct a free pages bitmap. The virtio-balloon driver is extended so as to send the free pages bitmap to QEMU for live migration optimization. Performance data ================ Test environment: CPU: Intel (R) Xeon(R) CPU ES-2699 v3 @ 2.30GHz Host RAM: 64GB Host Linux Kernel: 4.2.0 Host OS: CentOS 7.1 Guest Linux Kernel: 4.5.rc6 Guest OS: CentOS 6.6 Network: X540-AT2 with 10 Gigabit connection Guest RAM: 8GB Case 1: Idle guest just boots: ============================================ | original | pv ------------------------------------------- total time(ms) | 1894 | 421 -------------------------------------------- transferred ram(KB) | 398017 | 353242 ============================================ Case 2: The guest has ever run some memory consuming workload, the workload is terminated just before live migration. ============================================ | original | pv ------------------------------------------- total time(ms) | 7436 | 552 -------------------------------------------- transferred ram(KB) | 8146291 | 361375 ============================================ Liang Li (2): mm: Add the functions used to get free pages information virtio-balloon: extend balloon driver to support a new feature drivers/virtio/virtio_balloon.c | 108 ++++++++++++++++++++++++++++++++++-- include/uapi/linux/virtio_balloon.h | 1 + mm/page_alloc.c | 58 +++++++++++++++++++ 3 files changed, 162 insertions(+), 5 deletions(-) -- 1.8.3.1