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=-4.8 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 3C400C47082 for ; Sat, 5 Jun 2021 16:06:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 22EBD6140B for ; Sat, 5 Jun 2021 16:06:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230073AbhFEQIi (ORCPT ); Sat, 5 Jun 2021 12:08:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43544 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229930AbhFEQIg (ORCPT ); Sat, 5 Jun 2021 12:08:36 -0400 Received: from mail-ot1-x332.google.com (mail-ot1-x332.google.com [IPv6:2607:f8b0:4864:20::332]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4DFB0C061766; Sat, 5 Jun 2021 09:06:37 -0700 (PDT) Received: by mail-ot1-x332.google.com with SMTP id h24-20020a9d64180000b029036edcf8f9a6so12212382otl.3; Sat, 05 Jun 2021 09:06:37 -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=hsUvo0Z31jHzTyWdPjams5W26nQJVQkDf7AjZ09gvvE=; b=m9kPfzBycC3YKOIS3oTGC+mz9M6QD9nWpdY+FEYYsQQqupPC0rDpP2NxFTw/t4I+GQ Izga7S2Lgj2/pFSbCRYAx0DYbPAS88YcZhMb1L5T0QrPnj8Oxy06Vebsdvbl3jrt40Zx tUbfohpD7ZO1reTbhit9yiGi0PC8qm5sZ6LFDCJ4iOFFixmKCEGfxiARED2LEmzlpTDE io+IRZjwh6FMvvFwPQeMn4oy/EXc8Gv4teeLtkSVSSk2ao6mEvcqTeL5UhBFU7tKGJ08 I2iRL1/TGLiY2CByVGEQoK1DhUReOWRRYwBpIGOhc6XUI0WzNt1afSOY+nzhX4m2w68u 0izA== 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=hsUvo0Z31jHzTyWdPjams5W26nQJVQkDf7AjZ09gvvE=; b=g4aRNRoygleR19zOQXv/YHI8NSG/G6+UT5qkWgScT3yWuYGyIahAEgQJWUnJn7lKz1 RfGJO/Q/jVK0hPzxZuwl3LNePdAyXHk+zrDxEM7bHJSmiWSCPe/3/jZt1P9Go0RgymOX JTONBZBEWubG+z8bsdk8KJ4g0xTolX9pmpNsdPeRqB3Gf9UAPnWHqUX4r8Hq/VuI7IDq avl3t4q8QoNAnnVqKWusi21LhvrJFEbSd3C3GtUzAoNqpYrzqD5Nu1OYtRuyKSZXQjLV qCyA3xK7qkinc+7sbaHQH+jokSbwNpUzaWSvBNH17uwYlbe9WiybgWJv+kEa117N2ez4 0M9g== X-Gm-Message-State: AOAM532XmyqCfzK34UpjMMg+vUBfupJjDU6yJM0GHvyQWwxgDzlCP9DY uORKkxz5ZROnO9eZPM0sC6U= X-Google-Smtp-Source: ABdhPJxbglEED8yHHBv9b4qHkZGzEGhMuNGEOQ5HAC6n9QkPLmPeHoddwQhhjIdxRMn2SRlpIzi9xw== X-Received: by 2002:a9d:870:: with SMTP id 103mr1920466oty.44.1622909195740; Sat, 05 Jun 2021 09:06:35 -0700 (PDT) Received: from Davids-MacBook-Pro.local ([8.48.134.22]) by smtp.googlemail.com with ESMTPSA id q26sm1200218otn.0.2021.06.05.09.06.31 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 05 Jun 2021 09:06:35 -0700 (PDT) Subject: Re: [PATCH net-next v6 3/5] page_pool: Allow drivers to hint on SKB recycling To: Ilias Apalodimas , Yunsheng Lin Cc: Matteo Croce , netdev@vger.kernel.org, linux-mm@kvack.org, Ayush Sawal , Vinay Kumar Yadav , Rohit Maheshwari , "David S. Miller" , Jakub Kicinski , Thomas Petazzoni , Marcin Wojtas , Russell King , Mirko Lindner , Stephen Hemminger , Tariq Toukan , Jesper Dangaard Brouer , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Boris Pismenny , Arnd Bergmann , Andrew Morton , "Peter Zijlstra (Intel)" , Vlastimil Babka , Yu Zhao , Will Deacon , Fenghua Yu , Roman Gushchin , Hugh Dickins , Peter Xu , Jason Gunthorpe , Jonathan Lemon , Alexander Lobakin , Cong Wang , wenxu , Kevin Hao , Jakub Sitnicki , Marco Elver , Willem de Bruijn , Miaohe Lin , Guillaume Nault , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, Matthew Wilcox , Eric Dumazet , Lorenzo Bianconi , Saeed Mahameed , Andrew Lunn , Paolo Abeni , Sven Auhagen References: <20210521161527.34607-1-mcroce@linux.microsoft.com> <20210521161527.34607-4-mcroce@linux.microsoft.com> From: David Ahern Message-ID: <722e5567-d8ee-228c-978e-9d5966257bb1@gmail.com> Date: Sat, 5 Jun 2021 10:06:30 -0600 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On 6/4/21 2:42 AM, Ilias Apalodimas wrote: > [...] >>> + /* Driver set this to memory recycling info. Reset it on recycle. >>> + * This will *not* work for NIC using a split-page memory model. >>> + * The page will be returned to the pool here regardless of the >>> + * 'flipped' fragment being in use or not. >>> + */ >> >> I am not sure I understand how does the last part of comment related >> to the code below, as there is no driver using split-page memory model >> will reach here because those driver will not call skb_mark_for_recycle(), >> right? >> > > Yes the comment is there to prohibit people (mlx5 only actually) to add the > recycling bit on their driver. Because if they do it will *probably* work > but they might get random corrupted packets which will be hard to debug. > What's the complexity for getting it to work with split page model? Since 1500 is the default MTU, requiring a page per packet means a lot of wasted memory.