From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6D21EC3279B for ; Sat, 30 Jun 2018 04:27:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2F57F245BC for ; Sat, 30 Jun 2018 04:27:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2F57F245BC Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932499AbeF3E1e (ORCPT ); Sat, 30 Jun 2018 00:27:34 -0400 Received: from mga12.intel.com ([192.55.52.136]:9423 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932137AbeF3E1a (ORCPT ); Sat, 30 Jun 2018 00:27:30 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 29 Jun 2018 21:27:29 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.51,289,1526367600"; d="scan'208";a="68963916" Received: from unknown (HELO [10.239.13.97]) ([10.239.13.97]) by orsmga001.jf.intel.com with ESMTP; 29 Jun 2018 21:27:15 -0700 Message-ID: <5B370797.1090700@intel.com> Date: Sat, 30 Jun 2018 12:31:19 +0800 From: Wei Wang User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.7.0 MIME-Version: 1.0 To: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, mhocko@kernel.org, akpm@linux-foundation.org CC: torvalds@linux-foundation.org, pbonzini@redhat.com, liliang.opensource@gmail.com, yang.zhang.wz@gmail.com, quan.xu0@gmail.com, nilal@redhat.com, riel@redhat.com, peterx@redhat.com Subject: Re: [PATCH v34 0/4] Virtio-balloon: support free page reporting References: <1529928312-30500-1-git-send-email-wei.w.wang@intel.com> In-Reply-To: <1529928312-30500-1-git-send-email-wei.w.wang@intel.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/25/2018 08:05 PM, Wei Wang wrote: > This patch series is separated from the previous "Virtio-balloon > Enhancement" series. The new feature, VIRTIO_BALLOON_F_FREE_PAGE_HINT, > implemented by this series enables the virtio-balloon driver to report > hints of guest free pages to the host. It can be used to accelerate live > migration of VMs. Here is an introduction of this usage: > > Live migration needs to transfer the VM's memory from the source machine > to the destination round by round. For the 1st round, all the VM's memory > is transferred. From the 2nd round, only the pieces of memory that were > written by the guest (after the 1st round) are transferred. One method > that is popularly used by the hypervisor to track which part of memory is > written is to write-protect all the guest memory. > > This feature enables the optimization by skipping the transfer of guest > free pages during VM live migration. It is not concerned that the memory > pages are used after they are given to the hypervisor as a hint of the > free pages, because they will be tracked by the hypervisor and transferred > in the subsequent round if they are used and written. > > * Tests > - Test Environment > Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz > Guest: 8G RAM, 4 vCPU > Migration setup: migrate_set_speed 100G, migrate_set_downtime 2 second > > - Test Results > - Idle Guest Live Migration Time (results are averaged over 10 runs): > - Optimization v.s. Legacy = 284ms vs 1757ms --> ~84% reduction According to Michael's comments, add one more set of data here: Enabling page poison with value=0, and enable KSM. The legacy live migration time is 1806ms (averaged across 10 runs), compared to the case with this optimization feature in use (i.e. 284ms), there is still around ~84% reduction. Best, Wei