From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx3-rdu2.redhat.com [66.187.233.73]) by dpdk.org (Postfix) with ESMTP id 585A61B7A9; Tue, 15 May 2018 15:50:58 +0200 (CEST) Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id E9B464007CC4; Tue, 15 May 2018 13:50:57 +0000 (UTC) Received: from [10.36.112.13] (unknown [10.36.112.13]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CF17E2024CBA; Tue, 15 May 2018 13:50:56 +0000 (UTC) To: Tiwei Bie Cc: dev@dpdk.org, jianfeng.tan@intel.com, mst@redhat.com, stable@dpdk.org References: <20180430155954.9939-1-maxime.coquelin@redhat.com> <20180503115634.feaimkzpnbodferd@debian> From: Maxime Coquelin Message-ID: Date: Tue, 15 May 2018 15:50:54 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0 MIME-Version: 1.0 In-Reply-To: <20180503115634.feaimkzpnbodferd@debian> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.78 on 10.11.54.4 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 15 May 2018 13:50:57 +0000 (UTC) X-Greylist: inspected by milter-greylist-4.5.16 (mx1.redhat.com [10.11.55.7]); Tue, 15 May 2018 13:50:57 +0000 (UTC) for IP:'10.11.54.4' DOMAIN:'int-mx04.intmail.prod.int.rdu2.redhat.com' HELO:'smtp.corp.redhat.com' FROM:'maxime.coquelin@redhat.com' RCPT:'' Subject: Re: [dpdk-dev] [PATCH] vhost: improve dirty pages logging performance X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 15 May 2018 13:50:58 -0000 Hi Tiwei, I just see I missed to reply to your comment on my commit message: On 05/03/2018 01:56 PM, Tiwei Bie wrote: > On Mon, Apr 30, 2018 at 05:59:54PM +0200, Maxime Coquelin wrote: >> This patch caches all dirty pages logging until the used ring index >> is updated. These dirty pages won't be accessed by the guest as >> long as the host doesn't give them back to it by updating the >> index. > Below sentence in above commit message isn't the reason why > we can cache the dirty page logging. Right? > > """ > These dirty pages won't be accessed by the guest as > long as the host doesn't give them back to it by updating the > index. That's my understanding. As long as the used index is not updated, the guest will not process the descs. If the migration converges between the time the descs are written, and the time the used index is updated on source side. Then the guest running on destination will not see the descriptors as used but as available, and so will be overwritten by the vhost backend on destination. Regards, Maxime