From mboxrd@z Thu Jan 1 00:00:00 1970 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=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 3A2CAC3A589 for ; Thu, 15 Aug 2019 16:46:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0E36720578 for ; Thu, 15 Aug 2019 16:46:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729009AbfHOQqk (ORCPT ); Thu, 15 Aug 2019 12:46:40 -0400 Received: from mga12.intel.com ([192.55.52.136]:55171 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726099AbfHOQqj (ORCPT ); Thu, 15 Aug 2019 12:46:39 -0400 X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga106.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 15 Aug 2019 09:46:36 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.64,389,1559545200"; d="scan'208";a="260867787" Received: from unknown (HELO [10.241.228.234]) ([10.241.228.234]) by orsmga001.jf.intel.com with ESMTP; 15 Aug 2019 09:46:35 -0700 Subject: Re: [PATCH bpf-next 0/5] Add support for SKIP_BPF flag for AF_XDP sockets To: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , magnus.karlsson@intel.com, netdev@vger.kernel.org, bpf@vger.kernel.org, intel-wired-lan@lists.osuosl.org, maciej.fijalkowski@intel.com, tom.herbert@intel.com References: <1565840783-8269-1-git-send-email-sridhar.samudrala@intel.com> From: "Samudrala, Sridhar" Message-ID: Date: Thu, 15 Aug 2019 09:46:35 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 8/15/2019 5:51 AM, Björn Töpel wrote: > On 2019-08-15 05:46, Sridhar Samudrala wrote: >> This patch series introduces XDP_SKIP_BPF flag that can be specified >> during the bind() call of an AF_XDP socket to skip calling the BPF >> program in the receive path and pass the buffer directly to the socket. >> >> When a single AF_XDP socket is associated with a queue and a HW >> filter is used to redirect the packets and the app is interested in >> receiving all the packets on that queue, we don't need an additional >> BPF program to do further filtering or lookup/redirect to a socket. >> >> Here are some performance numbers collected on >>    - 2 socket 28 core Intel(R) Xeon(R) Platinum 8180 CPU @ 2.50GHz >>    - Intel 40Gb Ethernet NIC (i40e) >> >> All tests use 2 cores and the results are in Mpps. >> >> turbo on (default) >> --------------------------------------------- >>                        no-skip-bpf    skip-bpf >> --------------------------------------------- >> rxdrop zerocopy           21.9         38.5 >> l2fwd  zerocopy           17.0         20.5 >> rxdrop copy               11.1         13.3 >> l2fwd  copy                1.9          2.0 >> >> no turbo :  echo 1 > /sys/devices/system/cpu/intel_pstate/no_turbo >> --------------------------------------------- >>                        no-skip-bpf    skip-bpf >> --------------------------------------------- >> rxdrop zerocopy           15.4         29.0 >> l2fwd  zerocopy           11.8         18.2 >> rxdrop copy                8.2         10.5 >> l2fwd  copy                1.7          1.7 >> --------------------------------------------- >> > > This work is somewhat similar to the XDP_ATTACH work [1]. Avoiding the > retpoline in the XDP program call is a nice performance boost! I like > the numbers! :-) I also like the idea of adding a flag that just does > what most AF_XDP Rx users want -- just getting all packets of a > certain queue into the XDP sockets. > > In addition to Toke's mail, I have some more concerns with the series: > > * AFAIU the SKIP_BPF only works for zero-copy enabled sockets. IMO, it >   should work for all modes (including XDP_SKB). This patch enables SKIP_BPF for AF_XDP sockets where an XDP program is attached at driver level (both zerocopy and copy modes) I tried a quick hack to see the perf benefit with generic XDP mode, but i didn't see any significant improvement in performance in that scenario. so i didn't include that mode. > > * In order to work, a user still needs an XDP program running. That's >   clunky. I'd like the behavior that if no XDP program is attached, >   and the option is set, the packets for a that queue end up in the >   socket. If there's an XDP program attached, the program has >   precedence. I think this would require more changes in the drivers to take XDP datapath even when there is no XDP program loaded. > > * It requires changes in all drivers. Not nice, and scales badly. Try >   making it generic (xdp_do_redirect/xdp_flush), so it Just Works for >   all XDP capable drivers. I tried to make this as generic as possible and make the changes to the driver very minimal, but could not find a way to avoid any changes at all to the driver. xdp_do_direct() gets called based after the call to bpf_prog_run_xdp() in the drivers. > > Thanks for working on this! > > > Björn > > [1] > https://lore.kernel.org/netdev/20181207114431.18038-1-bjorn.topel@gmail.com/ > > > >> Sridhar Samudrala (5): >>    xsk: Convert bool 'zc' field in struct xdp_umem to a u32 bitmap >>    xsk: Introduce XDP_SKIP_BPF bind option >>    i40e: Enable XDP_SKIP_BPF option for AF_XDP sockets >>    ixgbe: Enable XDP_SKIP_BPF option for AF_XDP sockets >>    xdpsock_user: Add skip_bpf option >> >>   drivers/net/ethernet/intel/i40e/i40e_txrx.c   | 22 +++++++++- >>   drivers/net/ethernet/intel/i40e/i40e_xsk.c    |  6 +++ >>   drivers/net/ethernet/intel/ixgbe/ixgbe_main.c | 20 ++++++++- >>   drivers/net/ethernet/intel/ixgbe/ixgbe_xsk.c  | 16 ++++++- >>   include/net/xdp_sock.h                        | 21 ++++++++- >>   include/uapi/linux/if_xdp.h                   |  1 + >>   include/uapi/linux/xdp_diag.h                 |  1 + >>   net/xdp/xdp_umem.c                            |  9 ++-- >>   net/xdp/xsk.c                                 | 43 ++++++++++++++++--- >>   net/xdp/xsk_diag.c                            |  5 ++- >>   samples/bpf/xdpsock_user.c                    |  8 ++++ >>   11 files changed, 135 insertions(+), 17 deletions(-) >>