[0/3] AF_XDP Preferred Busy Polling
Message ID | 20210224111852.11947-1-ciara.loftus@intel.com (mailing list archive) |
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Headers |
Return-Path: <dev-bounces@dpdk.org> X-Original-To: patchwork@inbox.dpdk.org Delivered-To: patchwork@inbox.dpdk.org Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id E6357A034F; Wed, 24 Feb 2021 12:49:05 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 8AB254069B; Wed, 24 Feb 2021 12:49:05 +0100 (CET) Received: from mga12.intel.com (mga12.intel.com [192.55.52.136]) by mails.dpdk.org (Postfix) with ESMTP id 8FB9840042 for <dev@dpdk.org>; Wed, 24 Feb 2021 12:49:03 +0100 (CET) IronPort-SDR: RpzaE05AQFXopFGcIS3T3wdx8x94b8dcGcRdBZVCRR1mnzKDUZkE6RfZhVg7pXwF4tD8AUqhaE 788iXBOfvwVA== X-IronPort-AV: E=McAfee;i="6000,8403,9904"; a="164359728" X-IronPort-AV: E=Sophos;i="5.81,202,1610438400"; d="scan'208";a="164359728" Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 24 Feb 2021 03:49:02 -0800 IronPort-SDR: 7T4oVMf9SNCNmnGdclVMfRTVNJNBEzwsvgJVunYdEBpeELM4wEYKDLtwiNSzeHuo7CJo0NT/1Z 4B6sF+vzfAgg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.81,202,1610438400"; d="scan'208";a="515592042" Received: from silpixa00399839.ir.intel.com (HELO localhost.localdomain) ([10.237.222.142]) by orsmga004.jf.intel.com with ESMTP; 24 Feb 2021 03:49:01 -0800 From: Ciara Loftus <ciara.loftus@intel.com> To: dev@dpdk.org Cc: Ciara Loftus <ciara.loftus@intel.com> Date: Wed, 24 Feb 2021 11:18:49 +0000 Message-Id: <20210224111852.11947-1-ciara.loftus@intel.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20210218092307.29575-1-ciara.loftus@intel.com> References: <20210218092307.29575-1-ciara.loftus@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8bit Subject: [dpdk-dev] [PATCH 0/3] AF_XDP Preferred Busy Polling X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions <dev.dpdk.org> List-Unsubscribe: <https://mails.dpdk.org/options/dev>, <mailto:dev-request@dpdk.org?subject=unsubscribe> List-Archive: <http://mails.dpdk.org/archives/dev/> List-Post: <mailto:dev@dpdk.org> List-Help: <mailto:dev-request@dpdk.org?subject=help> List-Subscribe: <https://mails.dpdk.org/listinfo/dev>, <mailto:dev-request@dpdk.org?subject=subscribe> Errors-To: dev-bounces@dpdk.org Sender: "dev" <dev-bounces@dpdk.org> |
Message
Loftus, Ciara
Feb. 24, 2021, 11:18 a.m. UTC
Single-core performance of AF_XDP at high loads can be poor because a heavily loaded NAPI context will never enter or allow for busy-polling. 1C testpmd rxonly (both IRQs and PMD on core 0): ./dpdk-testpmd -l 0-1 --vdev=net_af_xdp0,iface=eth0 --main-lcore=1 -- \ --forward-mode=rxonly 0.088Mpps In order to achieve decent performance at high loads, it is currently recommended ensure the IRQs for the netdev queue and the core running the PMD are different. 2C testpmd rxonly (IRQs on core 0, PMD on core 1): ./dpdk-testpmd -l 0-1 --vdev=net_af_xdp0,iface=eth0 --main-lcore=0 -- \ --forward-mode=rxonly 19.26Mpps However using an extra core is of course not ideal. The SO_PREFER_BUSY_POLL socket option was introduced in kernel v5.11 to help improve 1C performance. See [1]. This series sets this socket option on xsks created with DPDK (ie. instances of the AF_XDP PMD) unless explicitly disabled or not supported by the kernel. It was chosen to be enabled by default in order to bring the AF_XDP PMD in line with most other PMDs which execute on a single core. The following system and netdev settings are recommended in conjunction with busy polling: echo 2 | sudo tee /sys/class/net/eth0/napi_defer_hard_irqs echo 200000 | sudo tee /sys/class/net/eth0/gro_flush_timeout Re-running the 1C test with busy polling support and the above settings: ./dpdk-testpmd -l 0-1 --vdev=net_af_xdp0,iface=eth0 --main-lcore=1 -- \ --forward-mode=rxonly 10.45Mpps A new vdev arg is introduced called 'busy_budget' whose default value is 64. busy_budget is the value supplied to the kernel with the SO_BUSY_POLL_BUDGET socket option and represents the busy-polling NAPI budget ie. the number of packets the kernel will attempt to process in the netdev's NAPI context. To set the busy budget to 256: ./dpdk-testpmd --vdev=net_af_xdp0,iface=eth0,busy_budget=256 14.06Mpps If you still wish to run using 2 cores (one for PMD once for IRQs) it is recommended to disable busy polling to achieve optimal 2C performance: ./dpdk-testpmd --vdev=net_af_xdp0,iface=eth0,busy_budget=0 19.09Mpps RFC->v1: * Fixed behaviour of busy_budget=0 * Ensure we bail out if any of the new setsockopts fail [1] https://lwn.net/Articles/837010/ Ciara Loftus (3): net/af_xdp: Increase max batch size to 512 net/af_xdp: Use recvfrom() instead of poll() net/af_xdp: preferred busy polling doc/guides/nics/af_xdp.rst | 38 ++++++++++- drivers/net/af_xdp/compat.h | 13 ++++ drivers/net/af_xdp/rte_eth_af_xdp.c | 100 ++++++++++++++++++++++------ 3 files changed, 129 insertions(+), 22 deletions(-)