From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id F3F5BA0524; Tue, 1 Jun 2021 16:28:26 +0200 (CEST) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 7470240689; Tue, 1 Jun 2021 16:28:26 +0200 (CEST) Received: from shelob.oktetlabs.ru (shelob.oktetlabs.ru [91.220.146.113]) by mails.dpdk.org (Postfix) with ESMTP id 288D040041 for ; Tue, 1 Jun 2021 16:28:25 +0200 (CEST) Received: from [192.168.45.100] (unknown [188.242.7.54]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by shelob.oktetlabs.ru (Postfix) with ESMTPSA id 90F837F529; Tue, 1 Jun 2021 17:28:24 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 shelob.oktetlabs.ru 90F837F529 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=oktetlabs.ru; s=default; t=1622557704; bh=NfToeEQDHsDNbjt3r/5kZTdHv0teVHaoHOnn0LEoOEg=; h=Subject:To:Cc:References:From:Date:In-Reply-To; b=ZmAbf+PTLADsQ1Id1OyvA3otloXnCyisCk2qLgAH0tccEu+SlGXbDF32bKugnOfKJ vMlbkhU/Wecn/Mr2WCaBoYPZL+4HyucaKaVQglQ53sqly94lnmaMTs7U4TxGUBdBA9 vBOYLOb8xFR1avzn43BfzfVBLhih5b984uG2VgSw= To: Ilya Maximets , dev@dpdk.org Cc: Eli Britstein , Smadar Fuks , Hyong Youb Kim , Kishore Padmanabha , Ori Kam , Ajit Khaparde , Jerin Jacob , John Daley , Thomas Monjalon , Ferruh Yigit , Andrew Rybchenko References: <20210601111420.5549-1-ivan.malov@oktetlabs.ru> <8c4f559e-3430-e2d5-1199-f1d4f4a8546d@ovn.org> From: Ivan Malov Message-ID: <4ffdb830-53ce-6ae6-7271-3eeb546b78de@oktetlabs.ru> Date: Tue, 1 Jun 2021 17:28:24 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.8.0 MIME-Version: 1.0 In-Reply-To: <8c4f559e-3430-e2d5-1199-f1d4f4a8546d@ovn.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [RFC PATCH] ethdev: clarify flow action PORT ID semantics X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" Hi Ilya, Thank you for reviewing the proposal at such short notice. I'm afraid that prior discussions overlook the simple fact that the whole problem is not limited to just VF representors. Action PORT_ID is also used with respect to the admin PF's ethdev, which "represents itself" (and by no means it represents the underlying physical/network port). In this case, one cannot state that the application treats it as a physical port, just like one states that the application perceives representors as VFs themselves. Given these facts, it would not be quite right to just align the documentation with the de-facto action meaning assumed by OvS. On 01/06/2021 15:10, Ilya Maximets wrote: > On 6/1/21 1:14 PM, Ivan Malov wrote: >> By its very name, action PORT_ID means that packets hit an ethdev with the >> given DPDK port ID. At least the current comments don't state the opposite. >> That said, since port representors had been adopted, applications like OvS >> have been misusing the action. They misread its purpose as sending packets >> to the opposite end of the "wire" plugged to the given ethdev, for example, >> redirecting packets to the VF itself rather than to its representor ethdev. >> Another example: OvS relies on this action with the admin PF's ethdev port >> ID specified in it in order to send offloaded packets to the physical port. >> >> Since there might be applications which use this action in its valid sense, >> one can't just change the documentation to greenlight the opposite meaning. >> This patch adds an explicit bit to the action configuration which will let >> applications, depending on their needs, leverage the two meanings properly. >> Applications like OvS, as well as PMDs, will have to be corrected when the >> patch has been applied. But the improved clarity of the action is worth it. >> >> The proposed change is not the only option. One could avoid changes in OvS >> and PMDs if the new configuration field had the opposite meaning, with the >> action itself meaning delivery to the represented port and not to DPDK one. >> Alternatively, one could define a brand new action with the said behaviour. > > We had already very similar discussions regarding the understanding of what > the representor really is from the DPDK API's point of view, and the last > time, IIUC, it was concluded by a tech. board that representor should be > a "ghost of a VF", i.e. DPDK APIs should apply configuration by default to > VF and not to the representor device: > https://patches.dpdk.org/project/dpdk/cover/20191029185051.32203-1-thomas@monjalon.net/#104376 > This wasn't enforced though, IIUC, for existing code and semantics is still mixed. > > I still think that configuration should be applied to VF, and the same applies > to rte_flow API. IMHO, average application should not care if device is > a VF itself or its representor. Everything should work exactly the same. > I think this matches with the original idea/design of the switchdev functionality > in the linux kernel and also matches with how the average user thinks about > representor devices. > > If some specific use-case requires to distinguish VF from the representor, > there should probably be a separate special API/flag for that. > > Best regards, Ilya Maximets. > -- Ivan M