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=-6.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 9A983C43461 for ; Tue, 8 Sep 2020 01:22:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 615572193E for ; Tue, 8 Sep 2020 01:22:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="l5oEidU4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728295AbgIHBWp (ORCPT ); Mon, 7 Sep 2020 21:22:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:60814 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728272AbgIHBWm (ORCPT ); Mon, 7 Sep 2020 21:22:42 -0400 Received: from mail-io1-xd42.google.com (mail-io1-xd42.google.com [IPv6:2607:f8b0:4864:20::d42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4FA19C061573; Mon, 7 Sep 2020 18:22:42 -0700 (PDT) Received: by mail-io1-xd42.google.com with SMTP id h4so15406728ioe.5; Mon, 07 Sep 2020 18:22:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=GYsBegW1E1w/duSqDumQ/6BnVkxD+sj7KRg+kol7Kug=; b=l5oEidU4eqtXGLWGLe1fzYnlCUDss0wiSthgavfD3Ks/2ByU6oI+lRZfV6wcmbMaIm zpPJtrZOHi9kheoXQrloUsnaXWl2XWIusXpAwukjvo4YoBvF68JZcxjgCgLUBTknPcRW oZq7D8hBdTJqzaG/mYESCHT1WpGMw7+mnu/AtV8NrT1rcd7uKbCL14+oI0dsKgTgxZ+U uEh97oUWAXeyY33QnNjR6dTrEQwQ6c9B/3emFNKb765aCWWsXzChz1Ompoa68g0TcCA5 WDb7j/BiAUKKIXWFy7uLVUCwPiDqfLlDJmpiJjry46zFUm+0DXaVJ4aSzDArF/6HxhM/ 0wMQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=GYsBegW1E1w/duSqDumQ/6BnVkxD+sj7KRg+kol7Kug=; b=c8sf04au4W3mQalZcs+HdE7Rp5JtqfcKKRZG/CMlzdkopkb7MMGhNurWV6Rvv5sM9F 9Pot5Kmjbk/l+X7xmQZrJZF0wgiULgzaBS6/puXJDIo7gUvclpHqnpD+9BjNevMSf9So r7v7YXNw91nafqrtq45HZKpW86nrscv4lLIEL623x451s6hkEMy0PCXsz5622RvPsOo3 I60ZuZovCcAuuQ3ByQS6jMz/22wJ2thm65IFU7MjVVrn4sWnwE61oN0qgLueUEq5/vTT L/63ByLc2q7uocI4nZtuaB+gA/NSmgAGAzGWwDVQ09bxybLIekbkbC+B9NBbkH+mx+qJ Lesg== X-Gm-Message-State: AOAM532Il2eXN9HbLFuhB8fBNjL1IlYYq7a/WZ/7KNeDF7cGPxyP0nPe /m1gWWyiE3rcAsO6jG2RrZg= X-Google-Smtp-Source: ABdhPJwERJE2LQcnaY1cCja1hcI+xA8jnnTh2yEeIvsOumlVGQ+OPL6svAhcQHGsH+B5Gxm2xduyNA== X-Received: by 2002:a05:6638:2a6:: with SMTP id d6mr10971376jaq.132.1599528161672; Mon, 07 Sep 2020 18:22:41 -0700 (PDT) Received: from Davids-MacBook-Pro.local ([2601:282:803:7700:55f5:1bb7:a67a:a2c6]) by smtp.googlemail.com with ESMTPSA id m15sm2006038iow.9.2020.09.07.18.22.40 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 07 Sep 2020 18:22:40 -0700 (PDT) Subject: Re: [PATCH v2 net-next 1/9] xdp: introduce mb in xdp_buff/xdp_frame To: Jesper Dangaard Brouer Cc: Alexei Starovoitov , Lorenzo Bianconi , netdev@vger.kernel.org, bpf@vger.kernel.org, davem@davemloft.net, lorenzo.bianconi@redhat.com, echaudro@redhat.com, sameehj@amazon.com, kuba@kernel.org, john.fastabend@gmail.com, daniel@iogearbox.net, ast@kernel.org, shayagr@amazon.com, David Ahern , Ilias Apalodimas References: <1e8e82f72e46264b7a7a1ac704d24e163ebed100.1599165031.git.lorenzo@kernel.org> <20200904010705.jm6dnuyj3oq4cpjd@ast-mbp.dhcp.thefacebook.com> <20200904091939.069592e4@carbon> <1c3e478c-5000-1726-6ce9-9b0a3ccfe1e5@gmail.com> <20200904175946.6be0f565@carbon> <107260d3-1fea-b582-84d3-2d092f3112b1@gmail.com> <20200907200245.0cdb63f1@carbon> From: David Ahern Message-ID: <51b88537-877a-c6bb-b4fb-0d629f37c0e6@gmail.com> Date: Mon, 7 Sep 2020 19:22:39 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: <20200907200245.0cdb63f1@carbon> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 9/7/20 12:02 PM, Jesper Dangaard Brouer wrote: > >> ok, is there any alignment requirement? can frame_sz be number of 32-bit >> words? I believe bit shifts are cheap. > > No that is not possible, because some drivers and generic-XDP have a > fully dynamic frame_sz. > frame_sz represents allocated memory right? What is the real range that needs to be supported for frame_sz? Surely there is some upper limit, and I thought it was 64kB. Allocated memory will not be on an odd number, so fair to assume at a minimum it is a multiple of 2. correct? At a minimum we should be able to shift frame_sz by 1 which now covers 64kB in a u16.