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 C0CC041BAB; Thu, 2 Feb 2023 10:21:33 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 7FF41406A2; Thu, 2 Feb 2023 10:21:33 +0100 (CET) Received: from shelob.oktetlabs.ru (shelob.oktetlabs.ru [91.220.146.113]) by mails.dpdk.org (Postfix) with ESMTP id 983E940689 for ; Thu, 2 Feb 2023 10:21:32 +0100 (CET) Received: from [192.168.38.17] (aros.oktetlabs.ru [192.168.38.17]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits)) (No client certificate requested) by shelob.oktetlabs.ru (Postfix) with ESMTPSA id E673C50; Thu, 2 Feb 2023 12:21:31 +0300 (MSK) DKIM-Filter: OpenDKIM Filter v2.11.0 shelob.oktetlabs.ru E673C50 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=oktetlabs.ru; s=default; t=1675329692; bh=v5b0Bux8J4vNxAg7leZGzJyJ+/mWg2shhEJ0uM/lIw4=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=FY2dBNvPOlk5vpQUG/9AvxNFtYKBAcey20qeZgKQMrXW3Fc6wf7N4TJWRmskCAeUJ sf9Y1GF7YKIWFbwtG4eMriAG9zE1ktsl8ZGx1/AsO1PBnZv5R67IfXQfH0Rwki/ZII qWectfQlgIN4v9Mv9MijKbRacEQfpMc1vM3eBceQ= Message-ID: <0f546992-dbd8-6d86-3d87-015a3dae98ee@oktetlabs.ru> Date: Thu, 2 Feb 2023 12:21:31 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.6.0 Subject: Re: [PATCH v7] ethdev: add special flags when creating async transfer table Content-Language: en-US To: Thomas Monjalon , Ferruh Yigit Cc: Rongwei Liu , matan@nvidia.com, viacheslavo@nvidia.com, orika@nvidia.com, Aman Singh , Yuying Zhang , dev@dpdk.org, rasland@nvidia.com, jerinj@marvell.com References: <51e583ea-4446-fea5-af74-dfe75d37f05c@oktetlabs.ru> <6867333.18pcnM708K@thomas> <1f05e083-8b0c-4ebf-a0f8-0b3c559cbc8c@oktetlabs.ru> <2309073.BjyWNHgNrj@thomas> From: Andrew Rybchenko Organization: OKTET Labs In-Reply-To: <2309073.BjyWNHgNrj@thomas> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 On 2/1/23 16:48, Thomas Monjalon wrote: > 01/02/2023 12:38, Andrew Rybchenko: >> On 2/1/23 14:18, Thomas Monjalon wrote: >>> 01/02/2023 12:10, Andrew Rybchenko: >>>> On 2/1/23 13:58, Thomas Monjalon wrote: >>>>> 01/02/2023 11:17, Andrew Rybchenko: >>>>>> On 1/18/23 19:18, Thomas Monjalon wrote: >>>>>>> 18/01/2023 08:28, Andrew Rybchenko: >>>>>>>> On 11/14/22 14:59, Rongwei Liu wrote: >>>>>>>>> In case flow rules match only one kind of traffic in a flow table, >>>>>>>>> then optimization can be done via allocation of this table. >>>>>>>>> Such optimization is possible only if the application gives a hint >>>>>>>>> about its usage of the table during initial configuration. >>>>>>>>> >>>>>>>>> The transfer domain rules may process traffic from wire or vport, >>>>>>>>> which may correspond to two kinds of underlayer resources. >>>>>>>>> That's why the first two hints introduced in this patch are about >>>>>>>>> wire and vport traffic specialization. >>>>>>>>> Wire means traffic arrives from the uplink port while vport means >>>>>>>>> traffic initiated from VF/SF. >>>>>>>>> >>>>>>>>> There are two possible approaches for providing the hints. >>>>>>>>> Using IPv4 as an example: >>>>>>>>> 1. Use pattern item in both template table and flow rules. >>>>>>>>> >>>>>>>>> pattern_template: pattern ANY_VPORT / eth / ipv4 is 1.1.1.1 / end >>>>>>>>> async flow create: pattern ANY_VPORT / eth / ipv4 is 1.1.1.2 / end >>>>>>>>> >>>>>>>>> "ANY_VPORT" needs to be present in each flow rule even if it's >>>>>>>>> just a hint. No value to match because matching is already done by >>>>>>>>> IPv4 item. >>>>>>>>> >>>>>>>>> 2. Add special flags into table_attr. >>>>>>>>> >>>>>>>>> template_table 0 create table_id 0 group 1 transfer vport_orig >>>>>>>>> >>>>>>>>> Approach 1 needs to specify the pattern in each flow rule which wastes >>>>>>>>> memory and is not user friendly. >>>>>>>>> This patch takes the 2nd approach and introduces one new member >>>>>>>>> "specialize" into rte_flow_table_attr to indicate possible flow table >>>>>>>>> optimization. >>>>>>>> >>>>>>>> The above description is misleading. It alternates options (1) >>>>>>>> and (2), but in fact (2) requires (1) as well. >>>>>>> >>>>>>> Yes the above description may be misleading >>>>>>> and it seems you are misleaded :) >>>>>> >>>>>> It is not my intention. If it is only my problem, I'm OK to >>>>>> step back. >>>>> >>>>> It's OK to explain and check everything is OK, no worries. >>>>> Thanks for reviewing. >>>>> >>>>>>> I will explain below why the option (2) doesn't require (1). >>>>>>> I think we should apply the same example to both cases to make it clear: >>>>>>> >>>>>>> 1. Use pattern item in both template table and flow rules: >>>>>>> >>>>>>> template table 3 = transfer pattern ANY_VPORT / eth / ipv4 src is 255.255.255.255 / end >>>>>>> flow rule = template_table 3 pattern ANY_VPORT / eth / ipv4 src is 1.1.1.1 / end >>>>>>> >>>>>>> The pattern template 3 will be used only to match flows coming from vports. >>>>>>> ANY_VPORT needs to be present in each flow rule. >>>>>> >>>>>> It looks like I lost something here. Why do we need to specify >>>>>> it in each flow rule if the matching is already fixed in >>>>>> template table? >>>>> >>>>> I think that's how template tables are designed. >>>>> Ori, please could you point us to the relevant documentation? >>>>> >>>>>>> ANY_VPORT matching is redundant with IP src 1.1.1.1 because >>>>>>> the user knows 1.1.1.1 is the IP of a vport. >>>>>> >>>>>> What should happen if a packet with src IP 1.1.1.1 comes from >>>>>> the wire? Almost anything could come from network. >>>>> >>>>> It a packet comes from a wired port AND >>>>> the PMD did an optimization based on this hint, >>>>> then the packet could be not matched. >>>> >>>> So, the hint changes matching results and therefore becomes >>>> a strange (extra) matching criteria under specific >>>> circumstance. It sounds bad. >>> >>> In this case, the user made a wrong assumption. >>> If the user does not do a mistake, the behavior should be the same >>> whether the hint is used or ignored. >>> >>>> So, good application must use >>>> real (always) matching criteria when composing flow rules. >>> >>> Of course, nothing replaces matching criteria. >>> >>>> So, RTE flow API should provide a way to write a good >>>> application without extra pain. >>>> That's why I'm saying that (2) requires (1) anyway. >>> >>> I don't follow this sentence. >>> If you mean with hint, flow matching is still required, then yes, >>> this is what I emphasized in my rewrite of the case (2) below. >>> >>>> It does not say that hint is not required at all. >>>> It is still useful for resources usage optimization if >>>> application knows how it is going to use particular table. >>> >>> Yes, that's an optional optimization. >>> It should not change the rules, >>> and it should not change the functional behavior >>> if the user does not do mistakes. >> >> So, we basically agree on the topic, but my goal here is a bit >> bigger. Make it easier for a user to avoid mistakes. May be it >> is stupid goal :) and all efforts are vain. >> If we have a match item with similar functionality it would be >> easy to just put it into a pattern. Otherwise, it could be >> complicated, have high chances to be skipped and rely on >> implicit matching criteria imposed by the hint on the HW >> which takes it into account. > > We may highlight in the doc that the functional behaviour must not rely > on the hints. It is only optional optimization and effects may vary > with differents driver. > What do you think? I don't know what else to do about user mistakes :) As I said - add corresponding pattern items. Anyway, hint itself is OK and makes sense. Hopefully documentation highlights that pattern match is required. If so, Acked-by: Andrew Rybchenko