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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham 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 538EAC3F2C6 for ; Tue, 3 Mar 2020 18:43:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20CE420842 for ; Tue, 3 Mar 2020 18:43:58 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="X7BfWGri" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727064AbgCCSn5 (ORCPT ); Tue, 3 Mar 2020 13:43:57 -0500 Received: from mail-pj1-f67.google.com ([209.85.216.67]:35445 "EHLO mail-pj1-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725796AbgCCSn5 (ORCPT ); Tue, 3 Mar 2020 13:43:57 -0500 Received: by mail-pj1-f67.google.com with SMTP id s8so1746420pjq.0; Tue, 03 Mar 2020 10:43:55 -0800 (PST) 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=o2s52Qbl0PNhCadCB1otS0CYR1jnvtic2xAxRNSIjBg=; b=X7BfWGriW03csmGwkOK/EPLk6X/O3ojb1VmDipegqUUkTSABR777OpYleaW0jD22HU qxiGRSFjglAQ431Cd14AReuBcxWFR30+zjBalLrYGngIYzduhONovZl0Nqn5Ay0EjXkv sP/K6/QpycEnh+pb3/8CxSAWn6o5YmhSTj6Qaxvhvb+o02L+K9Ref98WvvyV3Fhk+gbC g3ClOdMOrFxes2NaPDabHuCpyjzFodjMEgRW1hcv1cL0scGpXz8bBuh186+uuWExz9+s Qem0HV3eKL8nboh63KVAz8wh4NJ2+bvoD+B+iTQM9SYOHa5jD7lEVz5W0HhiGkdjOHPq lU9w== 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=o2s52Qbl0PNhCadCB1otS0CYR1jnvtic2xAxRNSIjBg=; b=XOTIpCwTmObtmV15y01dRAvYdPTATXzuJEMa/GvKZI7Vj0A40kuMrlmXhud6X5fX9j ef9VTFHo/4B8lYDeCK81VFokqsbEUbs4Dm82+6sZ5J5FgY99LcyAQ1bd3+ZoHyZscP5I uPMLhteBDn5DyHmj7QkR1pxKZE48Hd/dMwI7ZzbXzf3wKnq0oQeb4qRZr5B5JkrXp7Fv 3C9mSMVkqaNWS45QUGFpbgVXakxMZr/SavVNT3RYWizJ+CBRNklEfMU/CcgJVb6Q+TIo xXjZhwnOCdTGb1rtMKwnXdvn6siB9O7MgA6QfyFLPdpUn3WVAVGXiH2JmRFk3ONq+ASx kLWA== X-Gm-Message-State: ANhLgQ0rmnctlQftXLYqvGYikMguuzeniyXoYomSxhj0lQ323NVjT7Mk sWnQ+E3s2CwkMO+wx7ku0N0= X-Google-Smtp-Source: ADFU+vsUyny+fBfrVhpEUVaZmXQduHWlJv7RRyAiZAxZJOGHDQVtwsB8Qu47ECO7SbtnHHKWSGFjvQ== X-Received: by 2002:a17:90b:1904:: with SMTP id mp4mr5595251pjb.110.1583261034899; Tue, 03 Mar 2020 10:43:54 -0800 (PST) Received: from ast-mbp ([2620:10d:c090:500::4:a0de]) by smtp.gmail.com with ESMTPSA id 196sm25561435pfy.86.2020.03.03.10.43.53 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 03 Mar 2020 10:43:53 -0800 (PST) Date: Tue, 3 Mar 2020 10:43:51 -0800 From: Alexei Starovoitov To: Jesper Dangaard Brouer Cc: bpf@vger.kernel.org, gamemann@gflclan.com, lrizzo@google.com, netdev@vger.kernel.org, Daniel Borkmann , Alexander Duyck , Ilias Apalodimas , Toke =?utf-8?Q?H=C3=B8iland-J=C3=B8rgensen?= Subject: Re: [bpf-next PATCH] xdp: accept that XDP headroom isn't always equal XDP_PACKET_HEADROOM Message-ID: <20200303184350.66uzruobalf3y76f@ast-mbp> References: <158323601793.2048441.8715862429080864020.stgit@firesoul> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <158323601793.2048441.8715862429080864020.stgit@firesoul> User-Agent: NeoMutt/20180223 Sender: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Tue, Mar 03, 2020 at 12:46:58PM +0100, Jesper Dangaard Brouer wrote: > The Intel based drivers (ixgbe + i40e) have implemented XDP with > headroom 192 bytes and not the recommended 256 bytes defined by > XDP_PACKET_HEADROOM. For generic-XDP, accept that this headroom > is also a valid size. > > Still for generic-XDP if headroom is less, still expand headroom to > XDP_PACKET_HEADROOM as this is the default in most XDP drivers. > > Tested on ixgbe with xdp_rxq_info --skb-mode and --action XDP_DROP: > - Before: 4,816,430 pps > - After : 7,749,678 pps > (Note that ixgbe in native mode XDP_DROP 14,704,539 pps) > > Signed-off-by: Jesper Dangaard Brouer > --- > include/uapi/linux/bpf.h | 1 + > net/core/dev.c | 4 ++-- > 2 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h > index 906e9f2752db..14dc4f9fb3c8 100644 > --- a/include/uapi/linux/bpf.h > +++ b/include/uapi/linux/bpf.h > @@ -3312,6 +3312,7 @@ struct bpf_xdp_sock { > }; > > #define XDP_PACKET_HEADROOM 256 > +#define XDP_PACKET_HEADROOM_MIN 192 why expose it in uapi? > /* User return codes for XDP prog type. > * A valid XDP program must return one of these defined values. All other > diff --git a/net/core/dev.c b/net/core/dev.c > index 4770dde3448d..9c941cd38b13 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -4518,11 +4518,11 @@ static u32 netif_receive_generic_xdp(struct sk_buff *skb, > return XDP_PASS; > > /* XDP packets must be linear and must have sufficient headroom > - * of XDP_PACKET_HEADROOM bytes. This is the guarantee that also > + * of XDP_PACKET_HEADROOM_MIN bytes. This is the guarantee that also > * native XDP provides, thus we need to do it here as well. > */ > if (skb_cloned(skb) || skb_is_nonlinear(skb) || > - skb_headroom(skb) < XDP_PACKET_HEADROOM) { > + skb_headroom(skb) < XDP_PACKET_HEADROOM_MIN) { > int hroom = XDP_PACKET_HEADROOM - skb_headroom(skb); this looks odd. It's comparing against 192, but doing math with 256. I guess that's ok, but needs a clear comment. How about just doing 'skb_headroom(skb) < 192' here. Or #define 192 right before this function with a comment about ixgbe?