From patchwork Thu Oct 25 07:40:52 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Xing, Beilei" X-Patchwork-Id: 47407 X-Patchwork-Delegate: qi.z.zhang@intel.com Return-Path: X-Original-To: patchwork@dpdk.org Delivered-To: patchwork@dpdk.org Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id C02F34CC5; Thu, 25 Oct 2018 09:39:39 +0200 (CEST) Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id B7718293B; Thu, 25 Oct 2018 09:39:37 +0200 (CEST) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga104.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 25 Oct 2018 00:39:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.54,423,1534834800"; d="scan'208";a="244219909" Received: from unknown (HELO dpdk9.sh.intel.com) ([10.67.118.52]) by orsmga004.jf.intel.com with ESMTP; 25 Oct 2018 00:39:35 -0700 From: Beilei Xing To: qi.z.zhang@intel.com Cc: dev@dpdk.org, stable@dpdk.org Date: Thu, 25 Oct 2018 15:40:52 +0800 Message-Id: <1540453252-128654-1-git-send-email-beilei.xing@intel.com> X-Mailer: git-send-email 2.5.5 Subject: [dpdk-dev] [PATCH] net/i40e: fix Rx instability with vector mode 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: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Previously, there is instability during vector Rx if descriptor number is not power of 2, e.g. process hang and some Rx packets are unexpectedly empty. That's because vector Rx mode assumes Rx descriptor number is power of 2 when doing bit mask. This patch allows vector mode only when the number of Rx descriptor is power of 2. Fixes: 8e109464c022 ("i40e: allow vector Rx and Tx usage") Fixes: a3c83a2527e1 ("net/i40e: enable runtime queue setup") Cc: stable@dpdk.org Signed-off-by: Beilei Xing --- doc/guides/nics/i40e.rst | 7 +++++++ drivers/net/i40e/i40e_rxtx.c | 18 +++++++++++++++++- 2 files changed, 24 insertions(+), 1 deletion(-) diff --git a/doc/guides/nics/i40e.rst b/doc/guides/nics/i40e.rst index ab3928a..bfacbd1 100644 --- a/doc/guides/nics/i40e.rst +++ b/doc/guides/nics/i40e.rst @@ -172,6 +172,13 @@ Runtime Config Options -w 84:00.0,use-latest-supported-vec=1 +Vector RX 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``. + Driver compilation and testing ------------------------------ diff --git a/drivers/net/i40e/i40e_rxtx.c b/drivers/net/i40e/i40e_rxtx.c index a827456..aa46d83 100644 --- a/drivers/net/i40e/i40e_rxtx.c +++ b/drivers/net/i40e/i40e_rxtx.c @@ -1735,10 +1735,17 @@ i40e_dev_rx_queue_setup_runtime(struct rte_eth_dev *dev, * i40e_set_rx_function. */ ad->rx_bulk_alloc_allowed = true; - ad->rx_vec_allowed = true; dev->data->scattered_rx = use_scattered_rx; if (use_def_burst_func) ad->rx_bulk_alloc_allowed = false; + /** + * Vector mode is allowed only when number of Rx queue + * descriptor is a power of 2. + */ + if ((rxq->nb_rx_desc & (rxq->nb_rx_desc - 1))) + ad->rx_vec_allowed = false; + else + ad->rx_vec_allowed = true; i40e_set_rx_function(dev); return 0; } @@ -1811,6 +1818,15 @@ i40e_dev_rx_queue_setup(struct rte_eth_dev *dev, return -EINVAL; } + /** + * Vector mode is allowed only when number of Rx queue + * descriptor is a power of 2. + */ + if ((nb_desc & (nb_desc - 1))) + ad->rx_vec_allowed = false; + else + ad->rx_vec_allowed = true; + /* Free memory if needed */ if (dev->data->rx_queues[queue_idx]) { i40e_dev_rx_queue_release(dev->data->rx_queues[queue_idx]);