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=-1.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 3B01AC43219 for ; Wed, 1 May 2019 08:14:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 079812081C for ; Wed, 1 May 2019 08:14:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="KjocuGTf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726077AbfEAIOp (ORCPT ); Wed, 1 May 2019 04:14:45 -0400 Received: from mail-yw1-f66.google.com ([209.85.161.66]:45802 "EHLO mail-yw1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726014AbfEAIOp (ORCPT ); Wed, 1 May 2019 04:14:45 -0400 Received: by mail-yw1-f66.google.com with SMTP id r139so7821195ywe.12 for ; Wed, 01 May 2019 01:14:45 -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=MmY19Z1QVEc3yW3mekSsham5SrWXgj5jq6qjwyvS1O8=; b=KjocuGTflWsf4c3Wp6N3CndW5yRamNFECeIHqqxxGk98i+G4ne8zwvpYp2pHoaQQo2 563cIGo39Dnf7SScSPM6O5XrOU0ltBBVErldG7zxk12bRNc9QgYWfrxHz2M3jOkGyDJl ifJ4r7A9EO6VTIMry8oeLnxDcHQ8UIdSJUqjaPQ2GcyYKguzROVN2iUDXGKQiqT1v9n2 euuVQd9kgwVzV/ulQAcMyRwoH/NyG6lcnyXtYAQ3Q0HtXLQnubSoEbNduCz0sHGUfuoE lzIjEjNpsh+qR6kGeHncfgOzMLp37q265pdUsODliehwd2QMYG2dArLS65ANtgjFOlqi GtiQ== 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=MmY19Z1QVEc3yW3mekSsham5SrWXgj5jq6qjwyvS1O8=; b=Kh6RMO7MeBCbRKyI9abVNRWzyF7P7Yxnyfs6hFoJy7DOLNy8fGb3cmBYGoFNBTn02s 41R7wvT5ql9HXhhXFY7E8L4Zbb0G9dm99Dm8wuPi29XlQnlsugapdC2V/SlAA0i9FmnW m3NE2HrBQtZPjgNbJRmF9Aw/ewUOsX+HFF6JdVp4YiZEoTUQo2pYMObnPMgUXhtY4Vbo 6+cXfIqZ3wKHMfmthaXMcElL57ETnkM99JSSzegJQx043+9BUJEBtLvak63crqcBP438 gQyjkUv/LWoIDPIw7fFGPyN/HHxaf19KaZa58fYYNP4OucLFiZeHVcorV6oVdfipaVeY vx1g== X-Gm-Message-State: APjAAAXFcX7fb081P836MfpUZE4xf/EL0GTXAbyCM4pCarqH6qavq0UA G21xO3JiIbySyu5jVOvWaV4lnlw9 X-Google-Smtp-Source: APXvYqya6VAL9fNseG8YBC0Q17tvGWgSbHVP7tbGkA9z4v6ls0qqA3KJ9VJJspNMhZ8rQDOz2oZFQg== X-Received: by 2002:a81:4b94:: with SMTP id y142mr48670461ywa.69.1556698484466; Wed, 01 May 2019 01:14:44 -0700 (PDT) Received: from [172.20.0.54] (adsl-173-228-226-134.prtc.net. [173.228.226.134]) by smtp.gmail.com with ESMTPSA id 205sm4125097ywl.13.2019.05.01.01.14.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 01 May 2019 01:14:42 -0700 (PDT) Subject: Re: [PATCH 0/5] Beginnings of skb_frag -> bio_vec conversion To: Matthew Wilcox , davem@davemloft.net Cc: hch@lst.de, netdev@vger.kernel.org References: <20190501041757.8647-1-willy@infradead.org> From: Eric Dumazet Message-ID: <639880c6-5703-857c-8a70-82fbb5a90238@gmail.com> Date: Wed, 1 May 2019 04:14:41 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190501041757.8647-1-willy@infradead.org> 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 4/30/19 9:17 PM, Matthew Wilcox wrote: > From: "Matthew Wilcox (Oracle)" > > It turns out there's a lot of accessors for the skb_frag, which would > make this conversion really easy if some drivers didn't bypass them. > This is what I've done so far; my laptop's not really beefy enough to > cope with changing skbuff.h too often ;-) > > This would be a great time to tell me I'm going about this all wrong. > I already found one problem in this patch set; some of the drivers should > have been converted to skb_frag_dma_map() instead of fixing the arguments > to dma_map_page(). But anyway, I need sleep. > I guess the missing part here is the "why" all this is done ? 32 bit hosts will have bigger skb_shared_info and this impacts sk_rcvbuf and sk_sndbuf limits. 17 * 4 are 68 extra bytes per skb.