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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Claudiu Manoil , Vinicius Costa Gomes , Kurt Kanzenbach , Jacob Keller , Jamal Hadi Salim , Cong Wang , Jiri Pirko Subject: Re: [PATCH v5 net-next 08/17] net/sched: mqprio: allow reverse TC:TXQ mappings Message-ID: References: <20230202003621.2679603-1-vladimir.oltean@nxp.com> <20230202003621.2679603-9-vladimir.oltean@nxp.com> Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230202003621.2679603-9-vladimir.oltean@nxp.com> X-ClientProxiedBy: AM3PR07CA0115.eurprd07.prod.outlook.com (2603:10a6:207:7::25) To PH0PR13MB4842.namprd13.prod.outlook.com (2603:10b6:510:78::6) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: PH0PR13MB4842:EE_|PH0PR13MB4780:EE_ X-MS-Office365-Filtering-Correlation-Id: c5476370-4bf9-4519-0209-08db060240b4 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:PH0PR13MB4842.namprd13.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230025)(4636009)(346002)(376002)(396003)(39840400004)(136003)(366004)(451199018)(2616005)(83380400001)(38100700002)(8676002)(66946007)(6916009)(44832011)(66476007)(8936002)(66556008)(41300700001)(7416002)(5660300002)(86362001)(2906002)(4326008)(478600001)(6486002)(6506007)(966005)(54906003)(6666004)(316002)(186003)(36756003)(6512007);DIR:OUT;SFP:1102; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?vZuRYDQSFz3Jm/8bjSE+XzQSzataMRa/CuybZyGwuRzoGmpMgOZqTVO4QIK3?= =?us-ascii?Q?9Y040MxX8atxsgbIoQFgVcs9PlI2Owf+NpKMbvCTYQPSEfpgesonGU95i/Ne?= =?us-ascii?Q?w38GxydXKrHoZE5QYamAFqh7AsciMyfDRMv30+VJSad1QR4SVIRFBFi1+g5C?= =?us-ascii?Q?zBpGBZiOjOa+/1IDiPEfoBO+hxyjwimwlWs+MAT4HI1bj3FxUcDrsrX4jvrC?= =?us-ascii?Q?ChCqcGvlIuF2AIgybvGAXA1GMmkwYPxkheKwOl1iYm0X1yCA0cjILVDtubn2?= =?us-ascii?Q?3yUlltVaL6eieBUoMBqLUy88QlZlU6snr/P4AVgV/UqHns7/aG4lIdaPRQqw?= =?us-ascii?Q?FhzlHabckEGpYRl1C7dRg6skCEnbxy5hA4an1S4mHRvEyM6MPEOCHQQne3aa?= =?us-ascii?Q?D+99fBDQYbwb/xZcZeFdsWd493LIDLeyCr0OLco7LzwWCNu+t/U4YopTc4N9?= =?us-ascii?Q?SpcbJw6iH24KSsf/QzXNlXKlk8uEJys69FUH0SHN71yMOZS8KMFs1c4nPhD9?= =?us-ascii?Q?jXP3W7pFZ7G8+im5+vXFmKSXJJ4xugl0Q1Wo0jIPFkX/r96btXE+z0/G2nqW?= =?us-ascii?Q?v3qsJut99woDQYFMe+O5yD1cSXBYUIaI15QkFcpC85bAnn7+pKvB7NjvYS8y?= =?us-ascii?Q?kAxeLMt9YHKiTjHYywRnOrR4/eXjwFjgbAal8+QF+K7mbghw/Bl3C6Ig7h3H?= =?us-ascii?Q?2rY/Hh+HAu9NGvfZ75QO2wCPFNKOe9g91oy3b6YoMx0sQ+LNujEF6AZNFR+A?= =?us-ascii?Q?ibAgDzg42boGqzkrNZbCrkjmm/Jf/qbK/95pQkZRarCXTiPZ3MC5aTjBYI2+?= =?us-ascii?Q?vlQ0sKalRnCk6eavL1JaD8bq805LupZ9+NnmGECJ/ut26oW3w8S9xz7Lt8+K?= =?us-ascii?Q?lsLZN8ZCbFPzBoDteBZ9trbFDsYloWxrYaEpIVvThn7umxIupRU/8z9Qxywn?= =?us-ascii?Q?YFdMikfeF9P2cCFevEtwrz330w4TFMUMUyQ28DzqtjCtNlZ2q0OKQZJJ5ZHi?= =?us-ascii?Q?NNAWDaV3ikcY/bestFr/Kao0nnQE3TnH2mBt5ruAeXtoZMqKRIs7kXlrEl4z?= =?us-ascii?Q?UWZu2yb2Bnt5qgAomINE8Kq6deeFrs4DwzjCz6cZqZUecONYd4SuMteeRXzG?= =?us-ascii?Q?qzjxatwBDRt1ZL3U5mQwy5ggz6S+7MgPQgg1kLq78gxqW7wlTrZKx81ZBv/Z?= =?us-ascii?Q?sJUO7Nf76gZ4bLlvKMbnWaElEfTW8L5W7ubU3WXdXjGD34BW8nP+vLPl7Eud?= =?us-ascii?Q?6WSUomYutit9OuAPt5WdxN7ZZrmSfrxd4jO+ivWsdD3QxsSL1mw7W/JRhqgd?= =?us-ascii?Q?Z3nNoCvg6BYRauclMh0Nxl+BGFH+2g2nF/bIsln4z42R6hZYz/l2fwVKhExR?= =?us-ascii?Q?71SszZQBYrx3/WZ9woaTCrA1NqfSralC+gNjlE95sctzi3DU3p2hNrTkgzqm?= =?us-ascii?Q?GAuTK4GX4d0FUtR2AxQsvd+abDQo0ujGD3yS1Ud7A9KEhrNVMpGIlbfnJ7iL?= =?us-ascii?Q?bJgxjIRhIBJ+qPE5qIe/ZDPO3tQjTaJMVXaVhW5sTb6QhIALzMP8Bi1fIj98?= =?us-ascii?Q?WYx3yXBjy3Jp8RnAkno4vjg8hhgmnDZcbGW+f3ubvxqL+GEDKH/9l/SpEIlw?= =?us-ascii?Q?05VoNgEzEcUFAYjhGKo5hpmKDw1I9uBCYUGqfLwu74CpVXT48c37R6rdcJYA?= =?us-ascii?Q?J/cVdQ=3D=3D?= X-OriginatorOrg: corigine.com X-MS-Exchange-CrossTenant-Network-Message-Id: c5476370-4bf9-4519-0209-08db060240b4 X-MS-Exchange-CrossTenant-AuthSource: PH0PR13MB4842.namprd13.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 03 Feb 2023 16:18:15.0328 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: fe128f2c-073b-4c20-818e-7246a585940c X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: Hp6tHpaiXoTCm4Hf/VbTYAXXVeqOOc8fJw6ZbVujOxCKIP8N5tI27twzPF+0V4628Qo9wE/qXAiDl1OcAzVdcu1t06AsHCeip1Fko9Li5Hw= X-MS-Exchange-Transport-CrossTenantHeadersStamped: PH0PR13MB4780 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Thu, Feb 02, 2023 at 02:36:12AM +0200, Vladimir Oltean wrote: > By imposing that the last TXQ of TC i is smaller than the first TXQ of > any TC j (j := i+1 .. n), mqprio imposes a strict ordering condition for > the TXQ indices (they must increase as TCs increase). > > Claudiu points out that the complexity of the TXQ count validation is > too high for this logic, i.e. instead of iterating over j, it is > sufficient that the TXQ indices of TC i and i + 1 are ordered, and that > will eventually ensure global ordering. > > This is true, however it doesn't appear to me that is what the code > really intended to do. Instead, based on the comments, it just wanted to > check for overlaps (and this isn't how one does that). > > So the following mqprio configuration, which I had recommended to > Vinicius more than once for igb/igc (to account for the fact that on > this hardware, lower numbered TXQs have higher dequeue priority than > higher ones): > > num_tc 4 map 0 1 2 3 queues 1@3 1@2 1@1 1@0 > > is in fact denied today by mqprio. > > The full story is that in fact, it's only denied with "hw 0"; if > hardware offloading is requested, mqprio defers TXQ range overlap > validation to the device driver (a strange decision in itself). > > This is most certainly a bug, but it's not one that has any merit for > being fixed on "stable" as far as I can tell. This is because mqprio > always rejected a configuration which was in fact valid, and this has > shaped the way in which mqprio configuration scripts got built for > various hardware (see igb/igc in the link below). Therefore, one could > consider it to be merely an improvement for mqprio to allow reverse > TC:TXQ mappings. > > Link: https://patchwork.kernel.org/project/netdevbpf/patch/20230130173145.475943-9-vladimir.oltean@nxp.com/#25188310 > Link: https://patchwork.kernel.org/project/netdevbpf/patch/20230128010719.2182346-6-vladimir.oltean@nxp.com/#25186442 > Signed-off-by: Vladimir Oltean Reviewed-by: Simon Horman