From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 254356B0003 for ; Fri, 2 Feb 2018 07:46:05 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 205so20250414pfw.4 for ; Fri, 02 Feb 2018 04:46:05 -0800 (PST) Received: from mga18.intel.com (mga18.intel.com. [134.134.136.126]) by mx.google.com with ESMTPS id d123si1398228pfg.188.2018.02.02.04.46.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 02 Feb 2018 04:46:03 -0800 (PST) Message-ID: <5A745E27.7070002@intel.com> Date: Fri, 02 Feb 2018 20:48:39 +0800 From: Wei Wang MIME-Version: 1.0 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: owner-linux-mm@kvack.org List-ID: 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 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org