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=-4.3 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 37858C43460 for ; Mon, 12 Apr 2021 02:07:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0B58C611AD for ; Mon, 12 Apr 2021 02:07:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236014AbhDLCHv (ORCPT ); Sun, 11 Apr 2021 22:07:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33640 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235844AbhDLCHq (ORCPT ); Sun, 11 Apr 2021 22:07:46 -0400 Received: from mail-pj1-x102a.google.com (mail-pj1-x102a.google.com [IPv6:2607:f8b0:4864:20::102a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8687AC061574; Sun, 11 Apr 2021 19:07:28 -0700 (PDT) Received: by mail-pj1-x102a.google.com with SMTP id b8-20020a17090a5508b029014d0fbe9b64so7935268pji.5; Sun, 11 Apr 2021 19:07:28 -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=bvjdp3ahuYju51q1+1qQFX0ZeyUR0vs0519xG53Vx3g=; b=FJ4uC3yngQfBOIp7kWe8Kv4Ks82Ny9wrp7bJ5obe9mTTNFUzUNZKzdSv6jIVMbg0D2 rB/TIw47uhPl5ogfaf06xZrno6KtwRyGKUWg9nb5AkHYal8IDu6CLVv6Qx64JUwz09MK xzzpactU935+/vNOwvkhPbrlrGBikxHS8/XwlJHgvfD35OOaQulY7V/dLYUvHpRT/2cF PR6ehdJb8M1nXOnjXvENbq7ec7VJuNrPnZNVoGBa79fouDiSsyziCXkrFbG9SCP5cjJ7 4k9EMGGxOaBa0lY6k0dbubGuG8uWKVt16yKuB071ECyYbbdqNhPGxxZnHwgqTw5E1I+X 9Szw== 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=bvjdp3ahuYju51q1+1qQFX0ZeyUR0vs0519xG53Vx3g=; b=DG3Fylyv5o4B8ZRTxzGI9F1klhbKu/nl8tnr29zeKH6POIHK8e67vFpAthzy7L4Lw0 4es4ix/Ku/kqyKjkTYFAq/jrTC2ytARFfTvs7l/Gd9l0l4rvAE1m6CDr/Ke9FxCp0kTg W2Yaq/sHz3fBcTdakrumtXnvlaTzhHRTBI02LxA2B66ogSlIFDxzccC5UCM6hnV0frbr ohMIQ+/7ZNVuTWnPXIw8FTYsvy7+KjRkB5e85bFrX0Lcl0s7amrLWgixu9hk5nAUBhpM 9omvitkUJQfA2uVi0TzSkT1igl4w/pPVVko8SarJu6+BmXNbBcz4CYStCdicIco9TyHd kpxw== X-Gm-Message-State: AOAM531oOzam5iyAez/BVKeXuSvKZLbgfrxrY+Oy4zHFP1B1h0GhfLOB EKyZKUZbZebDsxM9KnQlBGkMCkaQXFw= X-Google-Smtp-Source: ABdhPJy8uVAb8XEtbTDwjn6bmn/cVyjU2UOUGkuKYm9Cb+mdGGfVKp9AFmO7/0mZgbdaXekeYKrDcQ== X-Received: by 2002:a17:903:31cc:b029:e4:bd48:c8e3 with SMTP id v12-20020a17090331ccb02900e4bd48c8e3mr23579790ple.40.1618193246916; Sun, 11 Apr 2021 19:07:26 -0700 (PDT) Received: from [10.230.2.159] ([192.19.228.250]) by smtp.gmail.com with ESMTPSA id fs3sm8817579pjb.30.2021.04.11.19.07.11 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 11 Apr 2021 19:07:26 -0700 (PDT) Subject: Re: [PATCH RFC net-next 0/3] Multi-CPU DSA support To: Andrew Lunn , Marek Behun Cc: Ansuel Smith , netdev@vger.kernel.org, "David S. Miller" , Jakub Kicinski , Vivien Didelot , Vladimir Oltean , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eric Dumazet , Wei Wang , Cong Wang , Taehee Yoo , =?UTF-8?B?QmrDtnJuIFTDtnBlbA==?= , zhang kai , Weilong Chen , Roopa Prabhu , Di Zhu , Francis Laniel , linux-kernel@vger.kernel.org References: <20210410133454.4768-1-ansuelsmth@gmail.com> <20210411200135.35fb5985@thinkpad> From: Florian Fainelli Message-ID: Date: Sun, 11 Apr 2021 19:07:08 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Firefox/78.0 Thunderbird/78.9.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/11/2021 11:39 AM, Andrew Lunn wrote: > On Sun, Apr 11, 2021 at 08:01:35PM +0200, Marek Behun wrote: >> On Sat, 10 Apr 2021 15:34:46 +0200 >> Ansuel Smith wrote: >> >>> Hi, >>> this is a respin of the Marek series in hope that this time we can >>> finally make some progress with dsa supporting multi-cpu port. >>> >>> This implementation is similar to the Marek series but with some tweaks. >>> This adds support for multiple-cpu port but leave the driver the >>> decision of the type of logic to use about assigning a CPU port to the >>> various port. The driver can also provide no preference and the CPU port >>> is decided using a round-robin way. >> >> In the last couple of months I have been giving some thought to this >> problem, and came up with one important thing: if there are multiple >> upstream ports, it would make a lot of sense to dynamically reallocate >> them to each user port, based on which user port is actually used, and >> at what speed. >> >> For example on Turris Omnia we have 2 CPU ports and 5 user ports. All >> ports support at most 1 Gbps. Round-robin would assign: >> CPU port 0 - Port 0 >> CPU port 1 - Port 1 >> CPU port 0 - Port 2 >> CPU port 1 - Port 3 >> CPU port 0 - Port 4 >> >> Now suppose that the user plugs ethernet cables only into ports 0 and 2, >> with 1, 3 and 4 free: >> CPU port 0 - Port 0 (plugged) >> CPU port 1 - Port 1 (free) >> CPU port 0 - Port 2 (plugged) >> CPU port 1 - Port 3 (free) >> CPU port 0 - Port 4 (free) >> >> We end up in a situation where ports 0 and 2 share 1 Gbps bandwidth to >> CPU, and the second CPU port is not used at all. >> >> A mechanism for automatic reassignment of CPU ports would be ideal here. > > One thing you need to watch out for here source MAC addresses. I've > not looked at the details, so this is more a heads up, it needs to be > thought about. > > DSA slaves get there MAC address from the master interface. For a > single CPU port, all the slaves have the same MAC address. What > happens when you have multiple CPU ports? Does the slave interface get > the MAC address from its CPU port? It seems to be addressed by this part of patch 2: + if (ether_addr_equal(dev->dev_addr, master->dev_addr)) + eth_hw_addr_inherit(dev, cpu_dev); although this could create an interesting set of issues if done fully dynamically while the data path is active. > What happens when a slave moves > from one CPU interface to another CPU interface? Does its MAC address > change. ARP is going to be unhappy for a while? Also, how is the > switch deciding on which CPU port to use? Some switches are probably > learning the MAC address being used by the interface and doing > forwarding based on that. So you might need unique slave MAC > addresses, and when a slave moves, it takes it MAC address with it, > and you hope the switch learns about the move. But considered trapped > frames as opposed to forwarded frames. So BPDU, IGMP, etc. Generally, > you only have the choice to send such trapped frames to one CPU > port. So potentially, such frames are going to ingress on the wrong > port. Does this matter? What about multicast? How do you control what > port that ingresses on? What about RX filters on the master > interfaces? Could it be we added it to the wrong master? > > For this series to make progress, we need to know what has been > tested, and if all the more complex functionality works, not just > basic pings. Agreed. -- Florian