From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mailout4.w1.samsung.com (mailout4.w1.samsung.com [210.118.77.14]) by dpdk.org (Postfix) with ESMTP id 3B43FC46E for ; Mon, 27 Apr 2015 13:54:32 +0200 (CEST) Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTP id <0NNG002Y7RQUA070@mailout4.w1.samsung.com> for dev@dpdk.org; Mon, 27 Apr 2015 12:54:30 +0100 (BST) X-AuditID: cbfec7f5-f794b6d000001495-c0-553e237aa5ef Received: from eusync1.samsung.com ( [203.254.199.211]) by eucpsbgm2.samsung.com (EUCPMTA) with SMTP id 35.3D.05269.A732E355; Mon, 27 Apr 2015 12:54:34 +0100 (BST) Received: from localhost ([106.109.131.58]) by eusync1.samsung.com (Oracle Communications Messaging Server 7.0.5.31.0 64bit (built May 5 2014)) with ESMTPA id <0NNG00E8TRQTCD10@eusync1.samsung.com> for dev@dpdk.org; Mon, 27 Apr 2015 12:54:29 +0100 (BST) Date: Mon, 27 Apr 2015 14:54:22 +0300 From: Nikita Kalyazin To: dev@dpdk.org Message-id: <20150427115422.GI28809@kalyazin.rnd.samsung.ru> MIME-version: 1.0 Content-type: text/plain; charset=utf-8 Content-disposition: inline X-Priority: 3 User-Agent: Mutt/1.5.23 (2014-03-12) X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFupnluLIzCtJLcpLzFFi42I5/e/4Zd0qZbtQgwWrmSzefdrO5MDo8WvB UtYAxigum5TUnMyy1CJ9uwSujEX7zrIWTGWtmPPyN0sD43SWLkYODgkBE4mWdU5djJxAppjE hXvr2boYuTiEBJYyStzbeRvKaWOSeLt4MRtIFYuAqsTda53MIM1sAnoSp08Hg4RFBAQkPndC lAgLKEi8+vqECcTmFbCROD75CTuELSjxY/I9sL3MAuoSU6bkgoSZBaQlHv2dwQ5xA6/EjPan LCC2qICKxJUJb9knMPLNQtI9C6F7FpLuBYzMqxhFU0uTC4qT0nON9IoTc4tL89L1kvNzNzFC gunrDsalx6wOMQpwMCrx8CrMsA0VYk0sK67MPcQowcGsJMJ7QMkuVIg3JbGyKrUoP76oNCe1 +BCjNAeLkjjvzF3vQ4QE0hNLUrNTUwtSi2CyTBycUg2Ms/59cFq/Mf/kgTUtF403aNpYMvBd KnOavW/Oyo8JnBcEBey1rJ8mxfLvfbj+3pYeu8XyO0InyD+VD1P5OedevuGpJiWThLt3aj2n XVf/ZWiZ7Pez/6tq/tw/9XelhVwMl96Snm73IkLi6Nu3iR2av9P/B7seWnVb8EIZY+DtjIYT Sy7F20WJKrEUZyQaajEXFScCANRUQVAiAgAA Subject: [dpdk-dev] data copy in vhost-user X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 27 Apr 2015 11:54:32 -0000 Hi, As far as I understand, DPDK vhost-user implementation requires data copy for either RX or TX (rte_vhost_dequeue_burst() and rte_vhost_enqueue_burst()). It means that two data copies are needed to transfer a packet from one VM to another. Why is not it possible to eliminate one of the copies (e.g., rte_vhost_enqueue_burst() might set up a reference at vring descriptor to mbuf's data rather than copying the data)? -- Best regards, Nikita Kalyazin, n.kalyazin@samsung.com CE OS Group Samsung R&D Institute Russia Tel: +7 (495) 797-25-00 #3816 Tel: +7 (495) 797-25-03 Office #1501, 12-1, Dvintsev str., Moscow, 127018, Russia