From patchwork Tue Feb 16 11:38:08 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Lobakin X-Patchwork-Id: 383658 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AA065C433DB for ; Tue, 16 Feb 2021 11:40:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 56C6364DF0 for ; Tue, 16 Feb 2021 11:40:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230209AbhBPLku (ORCPT ); Tue, 16 Feb 2021 06:40:50 -0500 Received: from mail-40133.protonmail.ch ([185.70.40.133]:25232 "EHLO mail-40133.protonmail.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230307AbhBPLjB (ORCPT ); Tue, 16 Feb 2021 06:39:01 -0500 Date: Tue, 16 Feb 2021 11:38:08 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=pm.me; s=protonmail; t=1613475495; bh=7//j7y6xoZuLy2Ngmv+kjotOmXPJtO9KtcN3PXcUSkQ=; h=Date:To:From:Cc:Reply-To:Subject:From; b=UR4bFjUVK9exL1LGEM/AUDMtHefnF+AYxkSGYHfIuuTYibotYnneCzbLfSH25ETll 3sZ7j8t0yPcz+LQVqbPQgctzQBPqc/xUMQpD44biUTxn68PXOeAasfYoCI/JmDkirJ Ih+TBLt+inppDmtRCBP/XdqR+G3tn2q2OyuyY7WaUiZiqC/DWbSaZpJCh8Vm9hyaqg LQp5EnEkGVNvacnPk8Pu+Y4TrWLo9gD6Oxxc+yeoQDIMxAxGZkS5uIzcsf4rZPSPTm Rpk1Obtl8HfjPqOdHERYtF5qtMEf10jJqEmtupATBMFpFt/t7G3j8qgczwlCJLfdNA iz5yhj+A6ApaA== To: Magnus Karlsson , =?utf-8?q?Bj=C3=B6rn_T?= =?utf-8?b?w7ZwZWw=?= From: Alexander Lobakin Cc: "Michael S. Tsirkin" , Jason Wang , "David S. Miller" , Jakub Kicinski , Jonathan Lemon , Alexei Starovoitov , Daniel Borkmann , Jesper Dangaard Brouer , John Fastabend , Andrii Nakryiko , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Paolo Abeni , Eric Dumazet , Xuan Zhuo , Dust Li , Alexander Lobakin , virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org Reply-To: Alexander Lobakin Subject: [PATCH v4 bpf-next 0/6] xsk: build skb by page (aka generic zerocopy xmit) Message-ID: <20210216113740.62041-1-alobakin@pm.me> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org This series introduces XSK generic zerocopy xmit by adding XSK umem pages as skb frags instead of copying data to linear space. The only requirement for this for drivers is to be able to xmit skbs with skb_headlen(skb) == 0, i.e. all data including hard headers starts from frag 0. To indicate whether a particular driver supports this, a new netdev priv flag, IFF_TX_SKB_NO_LINEAR, is added (and declared in virtio_net as it's already capable of doing it). So consider implementing this in your drivers to greatly speed-up generic XSK xmit. The first two bits refactor netdev_priv_flags a bit to harden them in terms of bitfield overflow, as IFF_TX_SKB_NO_LINEAR is the last one that fits into unsigned int. The fifth patch adds headroom and tailroom reservations for the allocated skbs on XSK generic xmit path. This ensures there won't be any unwanted skb reallocations on fast-path due to headroom and/or tailroom driver/device requirements (own headers/descriptors etc.). The other three add a new private flag, declare it in virtio_net driver and introduce generic XSK zerocopy xmit itself. The main body of work is created and done by Xuan Zhuo. His original cover letter: v3: Optimized code v2: 1. add priv_flags IFF_TX_SKB_NO_LINEAR instead of netdev_feature 2. split the patch to three: a. add priv_flags IFF_TX_SKB_NO_LINEAR b. virtio net add priv_flags IFF_TX_SKB_NO_LINEAR c. When there is support this flag, construct skb without linear space 3. use ERR_PTR() and PTR_ERR() to handle the err v1 message log: --------------- This patch is used to construct skb based on page to save memory copy overhead. This has one problem: We construct the skb by fill the data page as a frag into the skb. In this way, the linear space is empty, and the header information is also in the frag, not in the linear space, which is not allowed for some network cards. For example, Mellanox Technologies MT27710 Family [ConnectX-4 Lx] will get the following error message: mlx5_core 0000:3b:00.1 eth1: Error cqe on cqn 0x817, ci 0x8, qn 0x1dbb, opcode 0xd, syndrome 0x1, vendor syndrome 0x68 00000000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000020: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000030: 00 00 00 00 60 10 68 01 0a 00 1d bb 00 0f 9f d2 WQE DUMP: WQ size 1024 WQ cur size 0, WQE index 0xf, len: 64 00000000: 00 00 0f 0a 00 1d bb 03 00 00 00 08 00 00 00 00 00000010: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00000020: 00 00 00 2b 00 08 00 00 00 00 00 05 9e e3 08 00 00000030: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 mlx5_core 0000:3b:00.1 eth1: ERR CQE on SQ: 0x1dbb I also tried to use build_skb to construct skb, but because of the existence of skb_shinfo, it must be behind the linear space, so this method is not working. We can't put skb_shinfo on desc->addr, it will be exposed to users, this is not safe. Finally, I added a feature NETIF_F_SKB_NO_LINEAR to identify whether the network card supports the header information of the packet in the frag and not in the linear space. ---------------- Performance Testing ------------ The test environment is Aliyun ECS server. Test cmd: ``` xdpsock -i eth0 -t -S -s ``` Test result data: size 64 512 1024 1500 copy 1916747 1775988 1600203 1440054 page 1974058 1953655 1945463 1904478 percent 3.0% 10.0% 21.58% 32.3%