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 DB29F4331B; Mon, 13 Nov 2023 14:19:16 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id B3A47402F0; Mon, 13 Nov 2023 14:19:16 +0100 (CET) Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by mails.dpdk.org (Postfix) with ESMTP id A0DD2402AE for ; Mon, 13 Nov 2023 14:19:15 +0100 (CET) Received: from frapeml100006.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4STVNW5tJRz6K92f; Mon, 13 Nov 2023 21:18:03 +0800 (CST) Received: from frapeml500007.china.huawei.com (7.182.85.172) by frapeml100006.china.huawei.com (7.182.85.201) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Mon, 13 Nov 2023 14:19:14 +0100 Received: from frapeml500007.china.huawei.com ([7.182.85.172]) by frapeml500007.china.huawei.com ([7.182.85.172]) with mapi id 15.01.2507.031; Mon, 13 Nov 2023 14:19:14 +0100 From: Konstantin Ananyev To: =?iso-8859-1?Q?Morten_Br=F8rup?= , taozj888 , Stephen Hemminger , "konstantin.v.ananyev@yandex.ru" CC: "dev@dpdk.org" Subject: RE: Re: [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option Thread-Topic: Re: [PATCH v3 1/2] examples/l3fwd: relax RSS requirement with option Thread-Index: AQHaFi6oQYwe9Ccq8U2NBCAR8YnRvbB4OlQA Date: Mon, 13 Nov 2023 13:19:14 +0000 Message-ID: <2f9e5942d33a48cc82e0b88a4a3b31ee@huawei.com> References: <20231112071611.101503-1-taozj888@163.com> <20231112071611.101503-2-taozj888@163.com> <20231112153349.202150ff@hermes.local> <2645794b.6331.18bc881a674.Coremail.taozj888@163.com> <98CBD80474FA8B44BF855DF32C47DC35E9F01A@smartserver.smartshare.dk> In-Reply-To: <98CBD80474FA8B44BF855DF32C47DC35E9F01A@smartserver.smartshare.dk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-originating-ip: [10.81.190.147] Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-CFilter-Loop: Reflected 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 >> Now the port Rx mq_mode had been set to RTE_ETH_MQ_RX_RSS >> by default, but some hw and/or virtual interface does not >> support the RSS and offload mode presupposed, e.g., some >> virtio interfaces in the cloud don't support >> RSS and the error msg may like: >>=20 >> virtio_dev_configure(): RSS support requested but not supported by >> the device >> Port0 dev_configure =3D -95 >>=20 >> So to enable the l3fwd running in that environment, the Rx mode requirem= ent >> can be relaxed to reflect the hardware feature reality here, and the l3f= wd >> can run smoothly then. >>=20 >> An option named "relax-rx-mode" is added to enable the relax action >> here, and it's disabled by default. >>=20 >> Signed-off-by: Trevor Tao > >Doesn't need to be an option. The application can just look at the offload >flags and quickly determine that if multiple queues are being used than >RSS is required. If device doesn't support RSS, then fallback to single >queue with a warning. > >Hi Stephen: > >I think the option here was suggested/required by=A0Konstantin Ananyev . >The discussion thread is listed below: > ">>>>Should we probably instead have a new commnad-line option to explicitl= y=20 >>>>disable RSS? >>>=20 >>>>Something like: '--no-rss' or so? >>> Trevor: the RSS capability for a certain port was got by the rte_eth_de= v_info_get() automatically, and we think the user should not care about its= status beforehand, but if it's missing, a warning notification for the deg= rade here would be proposed to make it run smoothly. >> >>Personally, I still think it would be better the user will >>have an ability to disable it explicitly. >>Same as l3fwd does now with 'parse-ptype'. >> > >[Morten]: The "relax-rx-mode" does not explicitly disable RSS, it enables = the behavior Stephen suggested: If RSS is not supported by the device, fall= back to single queue with a warning. We don't need an option >for this; it = should be the default behavior. >[Morten]: I think Konstantin was asking for an option "no-rss" (or "disabl= e-rss") to force use of single queue (disable RSS), regardless if the devic= e supports RSS or not. Yes, that what was my initial suggestion: let people explicitly disable RSS= if they want to. BTW, I think it wouldn't change number of HW queues in any way. It would just disable distribution of packets among HW queues based on RSS. Konstantin=20