From patchwork Fri Feb 26 05:56:41 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: "Chen, Jing D" X-Patchwork-Id: 10845 X-Patchwork-Delegate: thomas@monjalon.net Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [IPv6:::1]) by dpdk.org (Postfix) with ESMTP id E054E2BDA; Fri, 26 Feb 2016 06:56:51 +0100 (CET) Received: from mga11.intel.com (mga11.intel.com [192.55.52.93]) by dpdk.org (Postfix) with ESMTP id 3BE592BD9 for ; Fri, 26 Feb 2016 06:56:50 +0100 (CET) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga102.fm.intel.com with ESMTP; 25 Feb 2016 21:56:49 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.22,498,1449561600"; d="scan'208";a="659550789" Received: from shvmail01.sh.intel.com ([10.239.29.42]) by FMSMGA003.fm.intel.com with ESMTP; 25 Feb 2016 21:56:48 -0800 Received: from shecgisg004.sh.intel.com (shecgisg004.sh.intel.com [10.239.29.89]) by shvmail01.sh.intel.com with ESMTP id u1Q5uk31010086; Fri, 26 Feb 2016 13:56:46 +0800 Received: from shecgisg004.sh.intel.com (localhost [127.0.0.1]) by shecgisg004.sh.intel.com (8.13.6/8.13.6/SuSE Linux 0.8) with ESMTP id u1Q5uhV1004279; Fri, 26 Feb 2016 13:56:45 +0800 Received: (from jingche2@localhost) by shecgisg004.sh.intel.com (8.13.6/8.13.6/Submit) id u1Q5uhs2004275; Fri, 26 Feb 2016 13:56:43 +0800 From: "Chen Jing D(Mark)" To: dev@dpdk.org Date: Fri, 26 Feb 2016 13:56:41 +0800 Message-Id: <1456466201-4073-1-git-send-email-jing.d.chen@intel.com> X-Mailer: git-send-email 1.7.12.2 In-Reply-To: <1454741289-2965-1-git-send-email-jing.d.chen@intel.com> References: <1454741289-2965-1-git-send-email-jing.d.chen@intel.com> MIME-Version: 1.0 Subject: [dpdk-dev] =?utf-8?q?=5BPATCH_v3=5D_doc=3A_add_Vector_FM10K_intro?= =?utf-8?q?ductions?= 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" From: "Chen Jing D(Mark)" Add introductions on how to enable Vector FM10K Rx/Tx functions, the preconditions and assumptions on Rx/Tx configuration parameters. The new content also lists the limitations of vector, so app/customer can do better to select best Rx/Tx functions. Signed-off-by: Chen Jing D(Mark) Acked-by: John McNamara --- v3: - rebase to dpdk-next-16.04 - Minor change to reword a few sentences. v2: - rebase to latest repo - Reword a few sentences that not follow coding style. doc/guides/nics/fm10k.rst | 98 +++++++++++++++++++++++++++++++++++++++++++++ 1 files changed, 98 insertions(+), 0 deletions(-) diff --git a/doc/guides/nics/fm10k.rst b/doc/guides/nics/fm10k.rst index 4206b7f..b97f611 100644 --- a/doc/guides/nics/fm10k.rst +++ b/doc/guides/nics/fm10k.rst @@ -35,6 +35,104 @@ The FM10K poll mode driver library provides support for the Intel FM10000 (FM10K) family of 40GbE/100GbE adapters. +Vector PMD for FM10K +-------------------- + +Vector PMD (vPMD) uses Intel® SIMD instructions to optimize packet I/O. +It improves load/store bandwidth efficiency of L1 data cache by using a wider +SSE/AVX ''register (1)''. +The wider register gives space to hold multiple packet buffers so as to save +on the number of instructions when bulk processing packets. + +There is no change to the PMD API. The RX/TX handlers are the only two entries for +vPMD packet I/O. They are transparently registered at runtime RX/TX execution +if all required conditions are met. + +1. To date, only an SSE version of FM10K vPMD is available. + To ensure that vPMD is in the binary code, set + ``CONFIG_RTE_LIBRTE_FM10K_INC_VECTOR=y`` in the configure file. + +Some constraints apply as pre-conditions for specific optimizations on bulk +packet transfers. The following sections explain RX and TX constraints in the +vPMD. + + +RX Constraints +~~~~~~~~~~~~~~ + + +Prerequisites and Pre-conditions +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +For Vector RX it is assumed that the number of descriptor rings will be a power +of 2. With this pre-condition, the ring pointer can easily scroll back to the +head after hitting the tail without a conditional check. In addition Vector RX +can use this assumption to do a bit mask using ``ring_size - 1``. + + +Features not Supported by Vector RX PMD +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Some features are not supported when trying to increase the throughput in +vPMD. They are: + +* IEEE1588 + +* Flow director + +* Header split + +* RX checksum offload + +Other features are supported using optional MACRO configuration. They include: + +* HW VLAN strip + +* L3/L4 packet type + +To enable via ``RX_OLFLAGS`` use ``RTE_LIBRTE_FM10K_RX_OLFLAGS_ENABLE=y``. + +To guarantee the constraint, the following configuration flags in ``dev_conf.rxmode`` +will be checked: + +* ``hw_vlan_extend`` + +* ``hw_ip_checksum`` + +* ``header_split`` + +* ``fdir_conf->mode`` + + +RX Burst Size +^^^^^^^^^^^^^ + +As vPMD is focused on high throughput, it processes 4 packets at a time. So it assumes +that the RX burst should be greater than 4 packets per burst. It returns zero if using +``nb_pkt`` < 4 in the receive handler. If ``nb_pkt`` is not a multiple of 4, a +floor alignment will be applied. + + +TX Constraint +~~~~~~~~~~~~~ + +Features not Supported by TX Vector PMD +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +TX vPMD only works when ``txq_flags`` is set to ``FM10K_SIMPLE_TX_FLAG``. +This means that it does not support TX multi-segment, VLAN offload or TX csum +offload. The following MACROs are used for these three features: + +* ``ETH_TXQ_FLAGS_NOMULTSEGS`` + +* ``ETH_TXQ_FLAGS_NOVLANOFFL`` + +* ``ETH_TXQ_FLAGS_NOXSUMSCTP`` + +* ``ETH_TXQ_FLAGS_NOXSUMUDP`` + +* ``ETH_TXQ_FLAGS_NOXSUMTCP`` + Limitations -----------