From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751664AbeBBMqJ (ORCPT ); Fri, 2 Feb 2018 07:46:09 -0500 Received: from mga17.intel.com ([192.55.52.151]:35011 "EHLO mga17.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751416AbeBBMqD (ORCPT ); Fri, 2 Feb 2018 07:46:03 -0500 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.46,448,1511856000"; d="scan'208";a="24381714" Message-ID: <5A745E27.7070002@intel.com> Date: Fri, 02 Feb 2018 20:48:39 +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: "Michael S. Tsirkin" CC: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mhocko@kernel.org, akpm@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 Subject: Re: [PATCH v25 0/2] Virtio-balloon: support free page reporting References: <1516871646-22741-1-git-send-email-wei.w.wang@intel.com> <20180201211525-mutt-send-email-mst@kernel.org> In-Reply-To: <20180201211525-mutt-send-email-mst@kernel.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/02/2018 03:15 AM, Michael S. Tsirkin wrote: > On Thu, Jan 25, 2018 at 05:14:04PM +0800, 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. >> >> The second feature enables the optimization of the 1st round memory >> transfer - the hypervisor can skip the transfer of guest free pages in the >> 1st round. 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 next round if they are >> used and written. > Could you post performance numbers please? Yes, it was posted here https://lkml.org/lkml/2018/1/25/698 I just changed the host side to poll the vq so that we don't need kick in the driver, it works pretty well. I'll test a little bit more and post out a new version with new performance numbers attached in the cover letter. Best, Wei