From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-it1-f176.google.com (mail-it1-f176.google.com [209.85.166.176]) by dpdk.org (Postfix) with ESMTP id 8B7D81B10D for ; Mon, 4 Feb 2019 13:54:05 +0100 (CET) Received: by mail-it1-f176.google.com with SMTP id p197so20723138itp.0 for ; Mon, 04 Feb 2019 04:54:05 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=netronome-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=KjkboHmRM6Eh/bkiwzlrYwOmSgIAHa+zJGLB6+ajoRI=; b=1B6KBAzUpHb2dCPVftVHBAkBg/kXuHlBGr1hRkPyU8yKV+b0l4YU+KtdutBIibpzdX qMro9n8rnfzMMtS++03CuqMO/yqjE7IPk2TbB03XIIfW+S82ZmonExacukkf3W5Gpnn2 TwojkettdBAgAjU/n05frQYaUyQKgVSzPMgQwcg0zzIlnUXe06X24F6MtHqbAEFLpeEu FoeGklrCJTbyyQXC+LFMaBbOBrhp6rE/3fTiwhaD+vzO0RiGUSwz1Z3h04xQcIasLgBX L6viEOWo/yialzCYTgx8LY4vU1lepJlYGKjz5xpR/kw79wLHQ+me4n4KiRgOBHOFXYRl YWTA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=KjkboHmRM6Eh/bkiwzlrYwOmSgIAHa+zJGLB6+ajoRI=; b=Vf3nBs5nIOvSw7SyzjM1Ou4k/2d4sgRClXP11i27l+ymiDeRwKR23TOXzKpQJDPU01 qpfUVaNADmra0jI6OgzSc5BUrET4wF8g9F7Wugj/f8JZuAFyCLt2uiwl80bGu9H6KMPP LoAM2xzrfhfSs3p3r2FfPvdMnLhik6/VTaDwXfeqXj8lPtdFxD/8ng/QvAM9TfomvqpA CfJ31tg7jKsCvCrLpj9gk3PDu2g2mbf7t47HMSgegJMlGuJzXcsqmHbeuvjePwa6qHE9 LCZXIcmG0FOvHPV80r4pji0IIkniTVya1TvtEBJv5yQX0HVCk+T4tZARjDe3BFzGTNTd NRNg== X-Gm-Message-State: AHQUAubJHDcn5V/gft1jmdGDtt1NUjWJJy4LDrbkfFwIvZcRo/W62F3m 7Nr6Cs0e7sRlE8RasbWTLNgrkOY1dYlbV0xb8gwgbA== X-Google-Smtp-Source: AHgI3IaG+TNtAJrj0TpE690CCHhGGAWD9QMsEr6flq425UZ2d5jaOp0V4XIXa/jMy4cRyquwePh06bgUmxdvKUdVxZc= X-Received: by 2002:a6b:5905:: with SMTP id n5mr1174085iob.33.1549284844839; Mon, 04 Feb 2019 04:54:04 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Alejandro Lucero Date: Mon, 4 Feb 2019 12:53:53 +0000 Message-ID: To: Rami Rosen Cc: dev Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.15 Subject: Re: [dpdk-dev] A Question about the necessity of DPDK VF for Ethernet PMDs 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: Mon, 04 Feb 2019 12:54:05 -0000 On Mon, Feb 4, 2019 at 12:19 PM Rami Rosen wrote: > Hi, Alejandro, > > Thanks for you quick response. > > >When SRIOV is used by VMs, the slow path will always be faster (and > >with lower latency) with DPDK. > > Yes, I am referring primarily to the SRIOV case in my question, when > assigning PCI VF to a VM (most likely QEMU VM) > Can you please explain what you mean about slow path in this context ? > > First packets from a new VM connection will go through the slow path. With SRIOV and assuming OVS offload, that implies the NIC sending the first packet up to OVS through the PF and back down once OVS decides what to do with that flow (including likely some flow rule offload). > Not sure the OVS setup is relevant here, it seems (if I understand > correctly) that VFIO is more commonly used in OVS setups, > so this query is not relevant here (unless you use igb_uio which is less > common) > I do not understand what you mean. VFIO is preferred because it is the right way of doing IOMMU, and also the only way if OVS run as non-root. If you have VMs using SRIOV, you need something like OVS in the host, and here it comes the potential benefit of OVS DPDK, because any OVS required action will likely be faster. > According to > http://docs.openvswitch.org/en/latest/intro/install/dpdk/ > "VFIO is prefered to the UIO driver when using recent versions of DPDK. " > Regards, > Rami Rosen > > > >