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=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 88296CA9EA0 for ; Sat, 19 Oct 2019 00:14:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4A96621897 for ; Sat, 19 Oct 2019 00:14:57 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ldTrboT/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404083AbfJSAO4 (ORCPT ); Fri, 18 Oct 2019 20:14:56 -0400 Received: from mail-pf1-f195.google.com ([209.85.210.195]:45086 "EHLO mail-pf1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728453AbfJSAO4 (ORCPT ); Fri, 18 Oct 2019 20:14:56 -0400 Received: by mail-pf1-f195.google.com with SMTP id y72so4794235pfb.12; Fri, 18 Oct 2019 17:14:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=2p0wvcmy8kPh5h8Q4FHfhvyG+WG0R8zknv0uy5+Q2r8=; b=ldTrboT/pTXBFXpp1ihZqV1gJl0NM4BFvcLhy07GTaRLieiACpvUJDQxIvLCTCnHz9 FLiEXBh8SKxCs17NK1AZm+95rfYJjh9yUGTfwHhvy9/Fz9GtsiDjdSJLgE8514BjXKto GunwN62rCDi9XmW6B5a5DtKvh4TabE8KRi4neX0yKriklvvEriqehTQN/wpA5w2RVDQ+ HSSXa5IOTxJWtaoKeE802g6ZNFCL+W61/ienz0mC8LDuPt1ONkYttXMoC9ubamo3y1Dm cvljG+yjZkiiXhwpQMkcx8BE2mtBm0UbEzV7N2bN3QApQdK9fjsngG/p1Ue9vEmPJldQ fmgw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=2p0wvcmy8kPh5h8Q4FHfhvyG+WG0R8zknv0uy5+Q2r8=; b=M+YJycgIoBrRHtsf7ybQNduxAk5TdcpEc1eHC0DqPi+hVJb0b6Hx6sMWSxc57niuQe sB/AhPalh1HSdvGgIogiVWRnE4xlIvfHg3MNk6qomcrNdC7WEmdgDYs0Zr/RWNF7yLx5 I86e4fzG9wewxPTrMT8G0TvwihrKPODD6LXtf6scwR7nyDrlsPy/PDWc5oyTnH+d80JH 6Vno1wYn7tK3BoM/piZFL3lsbEfrmiOZh+L8Acd2O2MXRnwOZCrMFPW3cGv/q1lZV5iX TM3Jz/lJvtZyKGJIug7J3IsGsRKYFWs7iWQdP9z3tfc0fjNU+Qb6p2nC33d/jHH/RZYr LtWg== X-Gm-Message-State: APjAAAWVnm4hXp7xjNed2oe+soVtxRrP9OegjjTo50+XYaImSIRzTcM/ CUus3o3it7Y9R62bNhvsQ+rikui1 X-Google-Smtp-Source: APXvYqyP/tO+DnGtqdFz3JMfzJ86denwfNQF8BBxtUpp1ADePXxfLuSCv+kPlD8NjS11vD3oc9ZhyQ== X-Received: by 2002:a63:1b41:: with SMTP id b1mr12987185pgm.335.1571444094225; Fri, 18 Oct 2019 17:14:54 -0700 (PDT) Received: from ast-mbp ([2620:10d:c090:180::6038]) by smtp.gmail.com with ESMTPSA id l22sm6484749pgj.4.2019.10.18.17.14.52 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 18 Oct 2019 17:14:53 -0700 (PDT) Date: Fri, 18 Oct 2019 17:14:51 -0700 From: Alexei Starovoitov To: "Samudrala, Sridhar" Cc: Jakub Kicinski , "Karlsson, Magnus" , =?utf-8?B?QmrDtnJuIFTDtnBlbA==?= , Netdev , "bpf@vger.kernel.org" , intel-wired-lan , "Fijalkowski, Maciej" , "Herbert, Tom" Subject: Re: FW: [PATCH bpf-next 2/4] xsk: allow AF_XDP sockets to receive packets directly from a queue Message-ID: <20191019001449.fk3gnhih4nx724pm@ast-mbp> References: <1570515415-45593-1-git-send-email-sridhar.samudrala@intel.com> <1570515415-45593-3-git-send-email-sridhar.samudrala@intel.com> <3ED8E928C4210A4289A677D2FEB48235140134CE@fmsmsx111.amr.corp.intel.com> <2bc26acd-170d-634e-c066-71557b2b3e4f@intel.com> <2032d58c-916f-d26a-db14-bd5ba6ad92b9@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180223 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Oct 18, 2019 at 11:40:07AM -0700, Samudrala, Sridhar wrote: > > Perf report for "AF_XDP default rxdrop" with patched kernel - mitigations ON > ========================================================================== > Samples: 44K of event 'cycles', Event count (approx.): 38532389541 > Overhead Command Shared Object Symbol > 15.31% ksoftirqd/28 [i40e] [k] i40e_clean_rx_irq_zc > 10.50% ksoftirqd/28 bpf_prog_80b55d8a76303785 [k] bpf_prog_80b55d8a76303785 > 9.48% xdpsock [i40e] [k] i40e_clean_rx_irq_zc > 8.62% xdpsock xdpsock [.] main > 7.11% ksoftirqd/28 [kernel.vmlinux] [k] xsk_rcv > 5.81% ksoftirqd/28 [kernel.vmlinux] [k] xdp_do_redirect > 4.46% xdpsock bpf_prog_80b55d8a76303785 [k] bpf_prog_80b55d8a76303785 > 3.83% xdpsock [kernel.vmlinux] [k] xsk_rcv why everything is duplicated? Same code runs in different tasks ? > 2.81% ksoftirqd/28 [kernel.vmlinux] [k] bpf_xdp_redirect_map > 2.78% ksoftirqd/28 [kernel.vmlinux] [k] xsk_map_lookup_elem > 2.44% xdpsock [kernel.vmlinux] [k] xdp_do_redirect > 2.19% ksoftirqd/28 [kernel.vmlinux] [k] __xsk_map_redirect > 1.62% ksoftirqd/28 [kernel.vmlinux] [k] xsk_umem_peek_addr > 1.57% xdpsock [kernel.vmlinux] [k] xsk_umem_peek_addr > 1.32% ksoftirqd/28 [kernel.vmlinux] [k] dma_direct_sync_single_for_cpu > 1.28% xdpsock [kernel.vmlinux] [k] bpf_xdp_redirect_map > 1.15% xdpsock [kernel.vmlinux] [k] dma_direct_sync_single_for_device > 1.12% xdpsock [kernel.vmlinux] [k] xsk_map_lookup_elem > 1.06% xdpsock [kernel.vmlinux] [k] __xsk_map_redirect > 0.94% ksoftirqd/28 [kernel.vmlinux] [k] dma_direct_sync_single_for_device > 0.75% ksoftirqd/28 [kernel.vmlinux] [k] __x86_indirect_thunk_rax > 0.66% ksoftirqd/28 [i40e] [k] i40e_clean_programming_status > 0.64% ksoftirqd/28 [kernel.vmlinux] [k] net_rx_action > 0.64% swapper [kernel.vmlinux] [k] intel_idle > 0.62% ksoftirqd/28 [i40e] [k] i40e_napi_poll > 0.57% xdpsock [kernel.vmlinux] [k] dma_direct_sync_single_for_cpu > > Perf report for "AF_XDP direct rxdrop" with patched kernel - mitigations ON > ========================================================================== > Samples: 46K of event 'cycles', Event count (approx.): 38387018585 > Overhead Command Shared Object Symbol > 21.94% ksoftirqd/28 [i40e] [k] i40e_clean_rx_irq_zc > 14.36% xdpsock xdpsock [.] main > 11.53% ksoftirqd/28 [kernel.vmlinux] [k] xsk_rcv > 11.32% xdpsock [i40e] [k] i40e_clean_rx_irq_zc > 4.02% xdpsock [kernel.vmlinux] [k] xsk_rcv > 2.91% ksoftirqd/28 [kernel.vmlinux] [k] xdp_do_redirect > 2.45% ksoftirqd/28 [kernel.vmlinux] [k] xsk_umem_peek_addr > 2.19% xdpsock [kernel.vmlinux] [k] xsk_umem_peek_addr > 2.08% ksoftirqd/28 [kernel.vmlinux] [k] bpf_direct_xsk > 2.07% ksoftirqd/28 [kernel.vmlinux] [k] dma_direct_sync_single_for_cpu > 1.53% ksoftirqd/28 [kernel.vmlinux] [k] dma_direct_sync_single_for_device > 1.39% xdpsock [kernel.vmlinux] [k] dma_direct_sync_single_for_device > 1.22% ksoftirqd/28 [kernel.vmlinux] [k] xdp_get_xsk_from_qid > 1.12% ksoftirqd/28 [i40e] [k] i40e_clean_programming_status > 0.96% ksoftirqd/28 [i40e] [k] i40e_napi_poll > 0.95% ksoftirqd/28 [kernel.vmlinux] [k] net_rx_action > 0.89% xdpsock [kernel.vmlinux] [k] xdp_do_redirect > 0.83% swapper [i40e] [k] i40e_clean_rx_irq_zc > 0.70% swapper [kernel.vmlinux] [k] intel_idle > 0.66% xdpsock [kernel.vmlinux] [k] dma_direct_sync_single_for_cpu > 0.60% xdpsock [kernel.vmlinux] [k] bpf_direct_xsk > 0.50% ksoftirqd/28 [kernel.vmlinux] [k] xsk_umem_discard_addr > > Based on the perf reports comparing AF_XDP default and direct rxdrop, we can say that > AF_XDP direct rxdrop codepath is avoiding the overhead of going through these functions > bpf_prog_xxx > bpf_xdp_redirect_map > xsk_map_lookup_elem > __xsk_map_redirect > With AF_XDP direct, xsk_rcv() is directly called via bpf_direct_xsk() in xdp_do_redirect() I don't think you're identifying the overhead correctly. xsk_map_lookup_elem is 1% but bpf_xdp_redirect_map() suppose to call __xsk_map_lookup_elem() which is a different function: ffffffff81493fe0 T __xsk_map_lookup_elem ffffffff81492e80 t xsk_map_lookup_elem 10% for bpf_prog_80b55d8a76303785 is huge. It's the actual code of the program _without_ any helpers. How does the program actually look?