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=-0.8 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, URIBL_BLOCKED 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 4CC1DECE58E for ; Tue, 8 Oct 2019 08:47:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2579A205F4 for ; Tue, 8 Oct 2019 08:47:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="s5BLKOYm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730211AbfJHIrW (ORCPT ); Tue, 8 Oct 2019 04:47:22 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:35581 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730137AbfJHIrW (ORCPT ); Tue, 8 Oct 2019 04:47:22 -0400 Received: by mail-qk1-f195.google.com with SMTP id w2so15895467qkf.2; Tue, 08 Oct 2019 01:47:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=fEbtEhAEfJotxoHiDxf90K1SxeKU7aOyeAokgjoiW14=; b=s5BLKOYmB1f/bm8kTdDPkE/gZyquvlZ02+0aoYl3q+OPcs2IuhVXb0mSdTIVDq6W12 olCHqvjWvAAYVhtVJfbIoP0r8SCz2qfI+68WaYPOv9fLRXxNLisolb9k4Ji7oHJUYhG4 R5hszW8IY225CeRwCzlTiY6CWBo0Hkq65k4O/SCJmN+8m3wDIvcDiWJKgg201eV3K1qG 5fCsEKRlKF5Rj2aXt/uTZaG2ESkZOKiw26UP1ix7TRw+raJOpkPnNmdfHFb9RqAXOTUc XaucCVIgwOIagHVpk3b7y69frjmh+GqVXSo1Cc8fcVikQ+WiPR/1FNlfGYXn9uQ/mmWX mC6g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=fEbtEhAEfJotxoHiDxf90K1SxeKU7aOyeAokgjoiW14=; b=nIGre+Jr6WkfxIi9OTQ9bPyfL4fsuPvrfd/LQSKaImNkA+O51DuOF57VfNAHfJbPCd vvwKrsIyCEw+xBVee3Xb2CGpatXnwwrADTSXsUJDPbyA1Es21vzhaN9dN1gD2rr7S2AO VywCXswoWSpQ7rBz44L89iO2UhbAqnU+/zufBxeQP1WUvIxWJavfGQgHVRR/zrX3Cwz5 ZTLToF4MN74Kq3FElyDfEwZZhxlELHMcOma/vwYaSXceuWYT5Kfpi4puV3Chhnzy7uk1 u2ZQtgAZr+mmh+pJBs887W/l4pE1KFa4XosTQS1eppJ2vusbbhmuR6lCWXKHMT5j9Cls ltqA== X-Gm-Message-State: APjAAAVLzlOjNWhUAAfNJ+K9IHFv9M65OHV9nTs+eOfVCR87i1CvYS1k kAbje6aQdRTJ1Pr63OrxSXBuQZ8WA/OGMgCVUUc= X-Google-Smtp-Source: APXvYqwawXCJKLXg09yH8++kGFLLLYB7xi/bDdB/hwSiA6kDwvZgIRzAoTS3Z0oVwpLhjbhbGRJ0bcDP213gNnX+prU= X-Received: by 2002:a37:4b02:: with SMTP id y2mr27772546qka.493.1570524440934; Tue, 08 Oct 2019 01:47:20 -0700 (PDT) MIME-Version: 1.0 References: <1570515415-45593-1-git-send-email-sridhar.samudrala@intel.com> <1570515415-45593-3-git-send-email-sridhar.samudrala@intel.com> <875zkzn2pj.fsf@toke.dk> In-Reply-To: <875zkzn2pj.fsf@toke.dk> From: =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= Date: Tue, 8 Oct 2019 10:47:09 +0200 Message-ID: Subject: Re: [PATCH bpf-next 2/4] xsk: allow AF_XDP sockets to receive packets directly from a queue To: =?UTF-8?B?VG9rZSBIw7hpbGFuZC1Kw7hyZ2Vuc2Vu?= Cc: Sridhar Samudrala , "Karlsson, Magnus" , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , Netdev , bpf , intel-wired-lan , maciej.fijalkowski@intel.com, tom.herbert@intel.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Tue, 8 Oct 2019 at 08:59, Toke H=C3=B8iland-J=C3=B8rgensen wrote: > > Sridhar Samudrala writes: > > > int xdp_do_redirect(struct net_device *dev, struct xdp_buff *xdp, > > struct bpf_prog *xdp_prog) > > { > > struct bpf_redirect_info *ri =3D this_cpu_ptr(&bpf_redirect_info)= ; > > struct bpf_map *map =3D READ_ONCE(ri->map); > > + struct xdp_sock *xsk; > > + > > + xsk =3D xdp_get_direct_xsk(ri); > > + if (xsk) > > + return xsk_rcv(xsk, xdp); > > This is a new branch and a read barrier in the XDP_REDIRECT fast path. > What's the performance impact of that for non-XSK redirect? > The dependent-read-barrier in READ_ONCE? Another branch -- leave that to the branch-predictor already! ;-) No, you're right, performance impact here is interesting. I guess the same static_branch could be used here as well... > -Toke >