From patchwork Fri Aug 25 11:18:43 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ciara Loftus X-Patchwork-Id: 805845 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=openvswitch.org (client-ip=140.211.169.12; helo=mail.linuxfoundation.org; envelope-from=ovs-dev-bounces@openvswitch.org; receiver=) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3xdzGy0fwvz9sR9 for ; Fri, 25 Aug 2017 21:20:26 +1000 (AEST) Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 4674EACC; Fri, 25 Aug 2017 11:19:41 +0000 (UTC) X-Original-To: dev@openvswitch.org Delivered-To: ovs-dev@mail.linuxfoundation.org Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id A7308AB7 for ; Fri, 25 Aug 2017 11:19:39 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 6A1A0FC for ; Fri, 25 Aug 2017 11:19:11 +0000 (UTC) Received: from fmsmga005.fm.intel.com ([10.253.24.32]) by orsmga104.jf.intel.com with ESMTP; 25 Aug 2017 04:18:46 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.41,425,1498546800"; d="scan'208";a="143839398" Received: from sivswdev01.ir.intel.com (HELO localhost.localdomain) ([10.237.217.45]) by fmsmga005.fm.intel.com with ESMTP; 25 Aug 2017 04:18:46 -0700 From: Ciara Loftus To: dev@openvswitch.org Date: Fri, 25 Aug 2017 12:18:43 +0100 Message-Id: <1503659923-24322-3-git-send-email-ciara.loftus@intel.com> X-Mailer: git-send-email 1.7.0.7 In-Reply-To: <1503659923-24322-1-git-send-email-ciara.loftus@intel.com> References: <1503659923-24322-1-git-send-email-ciara.loftus@intel.com> X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, RP_MATCHES_RCVD autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Subject: [ovs-dev] [PATCH 2/2] netdev-dpdk: Enable optional dequeue zero copy for vHost User X-BeenThere: ovs-dev@openvswitch.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: ovs-dev-bounces@openvswitch.org Errors-To: ovs-dev-bounces@openvswitch.org Enabled per port like so: ovs-vsctl set Interface dpdkvhostuserclient0 options:dq-zero-copy=true Zero Copy can only be enabled/disabled when a vHost port is down. When packets from a vHost device with zero copy enabled are destined for a 'dpdk' port, the number of tx descriptors on that 'dpdk' port must be set to a smaller value. 128 is recommended. This can be achieved like so: ovs-vsctl set Interface dpdkport options:n_txq_desc=128 Signed-off-by: Ciara Loftus --- Documentation/topics/dpdk/vhost-user.rst | 24 +++++++++ NEWS | 4 +- lib/netdev-dpdk.c | 89 +++++++++++++++++++++++++++++++- vswitchd/vswitch.xml | 11 ++++ 4 files changed, 126 insertions(+), 2 deletions(-) diff --git a/Documentation/topics/dpdk/vhost-user.rst b/Documentation/topics/dpdk/vhost-user.rst index a3d5de3..937d83a 100644 --- a/Documentation/topics/dpdk/vhost-user.rst +++ b/Documentation/topics/dpdk/vhost-user.rst @@ -408,3 +408,27 @@ Sample XML .. _QEMU documentation: http://git.qemu-project.org/?p=qemu.git;a=blob;f=docs/specs/vhost-user.txt;h=7890d7169;hb=HEAD + +vhost-user Dequeue Zero Copy +------------------------------------- + +Normally when dequeuing a packet from a vHost User device, a memcpy operation +must be used to copy that packet from guest address space to host address +space. This memcpy can be removed by enabling dequeue zero-copy like so: + + $ ovs-vsctl set Interface dpdkvhostuserclient0 options:dq-zero-copy=true + +With this feature enabled, a reference (pointer) to the packet is passed to +the host, instead of a copy of the packet. Removing this memcpy can give a +performance improvement for some use cases, for example switching large packets +between different VMs. + +A limitation exists whereby if packets from a vHost port with dq-zero-copy=true +are destined for a 'dpdk' type port, the number of tx descriptors (n_txq_desc) +for that port must be reduced to a smaller number, 128 being the recommended +value. This can be achieved by issuing the following command: + + $ ovs-vsctl set Interface dpdkport options:n_txq_desc=128 + +Further information can be found in the +`DPDK documentation `__ diff --git a/NEWS b/NEWS index cbcfd8e..750e08a 100644 --- a/NEWS +++ b/NEWS @@ -1,6 +1,8 @@ Post-v2.8.0 -------------------- - - Nothing yet. + - DPDK: + * Optional dequeue zero copy feature for vHost ports enabled per port + via the boolean 'dq-zero-copy' option. v2.8.0 - xx xxx xxxx --------------------- diff --git a/lib/netdev-dpdk.c b/lib/netdev-dpdk.c index ade813b..b9c7fc4 100644 --- a/lib/netdev-dpdk.c +++ b/lib/netdev-dpdk.c @@ -381,6 +381,9 @@ struct netdev_dpdk { /* True if vHost device is 'up' and has been reconfigured at least once */ bool vhost_reconfigured; + /* True if dq-zero-copy feature has successfully been enabled */ + bool zc_enabled; + /* Identifier used to distinguish vhost devices from each other. */ char vhost_id[PATH_MAX]; @@ -879,6 +882,7 @@ common_construct(struct netdev *netdev, dpdk_port_t port_no, dev->max_packet_len = MTU_TO_FRAME_LEN(dev->mtu); ovsrcu_index_init(&dev->vid, -1); dev->vhost_reconfigured = false; + dev->zc_enabled = false; dev->attached = false; ovsrcu_init(&dev->qos_conf, NULL); @@ -1387,6 +1391,29 @@ netdev_dpdk_ring_set_config(struct netdev *netdev, const struct smap *args, return 0; } +static void +dpdk_vhost_set_config_helper(struct netdev_dpdk *dev, + const struct smap *args) +{ + bool needs_reconfigure = false; + bool zc_requested = smap_get_bool(args, "dq-zero-copy", false); + + if (zc_requested && + !(dev->vhost_driver_flags & RTE_VHOST_USER_DEQUEUE_ZERO_COPY)) { + dev->vhost_driver_flags |= RTE_VHOST_USER_DEQUEUE_ZERO_COPY; + needs_reconfigure = true; + } else if (!zc_requested && + (dev->vhost_driver_flags & RTE_VHOST_USER_DEQUEUE_ZERO_COPY)) { + dev->vhost_driver_flags &= ~RTE_VHOST_USER_DEQUEUE_ZERO_COPY; + needs_reconfigure = true; + } + + /* Only try to change ZC mode when device is down */ + if (needs_reconfigure && (netdev_dpdk_get_vid(dev) == -1)) { + netdev_request_reconfigure(&dev->up); + } +} + static int netdev_dpdk_vhost_client_set_config(struct netdev *netdev, const struct smap *args, @@ -1403,6 +1430,23 @@ netdev_dpdk_vhost_client_set_config(struct netdev *netdev, netdev_request_reconfigure(netdev); } } + + dpdk_vhost_set_config_helper(dev, args); + + ovs_mutex_unlock(&dev->mutex); + + return 0; +} + +static int +netdev_dpdk_vhost_set_config(struct netdev *netdev, + const struct smap *args, + char **errp OVS_UNUSED) +{ + struct netdev_dpdk *dev = netdev_dpdk_cast(netdev); + + ovs_mutex_lock(&dev->mutex); + dpdk_vhost_set_config_helper(dev, args); ovs_mutex_unlock(&dev->mutex); return 0; @@ -2717,6 +2761,46 @@ netdev_dpdk_txq_map_clear(struct netdev_dpdk *dev) } } +static void +vhost_change_zero_copy_mode(struct netdev_dpdk *dev, bool client_mode, + bool enable) +{ + int err = rte_vhost_driver_unregister(dev->vhost_id); + + if (err) { + VLOG_ERR("Error unregistering vHost socket %s; can't change zero copy " + "mode", dev->vhost_id); + } else { + err = dpdk_setup_vhost_device(dev, client_mode); + if (err) { + VLOG_ERR("Error changing zero copy mode for vHost socket %s", + dev->vhost_id); + } else if (enable) { + dev->zc_enabled = true; + VLOG_INFO("Zero copy enabled for vHost socket %s", dev->vhost_id); + } else { + dev->zc_enabled = false; + VLOG_INFO("Zero copy disabled for vHost socket %s", dev->vhost_id); + } + } +} + +static void +vhost_check_zero_copy_status(struct netdev_dpdk *dev) +{ + bool mode = dev->vhost_driver_flags & RTE_VHOST_USER_CLIENT; + + if ((dev->vhost_driver_flags & RTE_VHOST_USER_DEQUEUE_ZERO_COPY) + && !dev->zc_enabled) { + /* ZC disabled but requested to be enabled, enable it. */ + vhost_change_zero_copy_mode(dev, mode, true); + } else if (!(dev->vhost_driver_flags & + RTE_VHOST_USER_DEQUEUE_ZERO_COPY) && dev->zc_enabled) { + /* ZC enabled but requested to be disabled, disable it. */ + vhost_change_zero_copy_mode(dev, mode, false); + } +} + /* * Remove a virtio-net device from the specific vhost port. Use dev->remove * flag to stop any more packets from being sent or received to/from a VM and @@ -2762,6 +2846,7 @@ destroy_device(int vid) */ ovsrcu_quiesce_start(); VLOG_INFO("vHost Device '%s' has been removed", ifname); + netdev_request_reconfigure(&dev->up); } else { VLOG_INFO("vHost Device '%s' not found", ifname); } @@ -3253,6 +3338,8 @@ dpdk_vhost_reconfigure_helper(struct netdev_dpdk *dev) if (netdev_dpdk_get_vid(dev) >= 0) { dev->vhost_reconfigured = true; + } else { + vhost_check_zero_copy_status(dev); } return 0; @@ -3414,7 +3501,7 @@ static const struct netdev_class dpdk_vhost_class = NULL, netdev_dpdk_vhost_construct, netdev_dpdk_vhost_destruct, - NULL, + netdev_dpdk_vhost_set_config, NULL, netdev_dpdk_vhost_send, netdev_dpdk_vhost_get_carrier, diff --git a/vswitchd/vswitch.xml b/vswitchd/vswitch.xml index 074535b..660b46f 100644 --- a/vswitchd/vswitch.xml +++ b/vswitchd/vswitch.xml @@ -2621,6 +2621,17 @@

+ +

+ The value specifies whether or not to enable dequeue zero copy on + the given interface. + The port must be in an inactive state in order to enable or disable + this feature. + Only supported by dpdkvhostuserclient and dpdkvhostuser interfaces. +

+ +