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emacs 30.2 From: Petr Machata To: Jakub Kicinski CC: , , , , , , , , , , , , Subject: Re: [PATCH net-next v2 3/9] tools: ynltool: add qstats analysis for HW-GRO efficiency / savings Date: Mon, 9 Feb 2026 10:43:33 +0100 In-Reply-To: <20260207003509.3927744-4-kuba@kernel.org> Message-ID: <87o6lyz1xx.fsf@nvidia.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-ClientProxiedBy: rnnvmail202.nvidia.com (10.129.68.7) To rnnvmail201.nvidia.com (10.129.68.8) X-EOPAttributedMessage: 0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: BY1PEPF0001AE1D:EE_|DS7PR12MB6335:EE_ X-MS-Office365-Filtering-Correlation-Id: 37d4d4d9-e388-46b0-a14c-08de67bfd8bb X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|36860700013|1800799024|82310400026|7416014|376014; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?w7bnLfA6jUX3ai+GWKlGxpGDk2fowXpoDwGGCVsLocSpoqAnzM0nZlvPtSZx?= =?us-ascii?Q?631PCGBLOvpLIklqAtTNUFOUw2jUnifXZ7tSysKHNKRvtUq12wg82OWxlaGI?= =?us-ascii?Q?RalF6GF84QBHRgT537j/wyLg6UlHNeAwcitJWUKgUgOhdnb6UliupjR2X04J?= =?us-ascii?Q?LyfXdkWiOdm2JeaHzz42lHUMxhromVTBi1oDPdViGDAHTfXZTYJSWqDLdnHC?= =?us-ascii?Q?SOzNwTfEOlP9D4bPiGyeArY/ku9xi42sQ/ZfmbRAuk1GlEI4eMzGTdDx7aQE?= =?us-ascii?Q?GtyKowGaQh3TGSHHJLFeuIUkJttlkBDsF/kYiECGJEbH8OlaKkwMZc4BaTpm?= =?us-ascii?Q?vRLK9hIgSWzldDIxi4KbqoLDZp8qswV/skDe8DGMTrnX0l4oO4cKzYiNTslk?= =?us-ascii?Q?eCpDYozgEn6dqnq2obsvu7usk9NioTHDHGQTnxJIzTj+dFuL0zi2WavS2GZe?= =?us-ascii?Q?taEQ0Pkm5sSxwp9LAHNc0v8P+r3v5EVPf/oJfPIRF53b7PEK6UGPI54PO24N?= =?us-ascii?Q?yEU/DHMOPrV4jtD7ZFAvC/ijI5k+mMxJK8Ef79jUv4LTcM8wwk1b5+9DCI97?= =?us-ascii?Q?HUPBRGaTJdHyhoHF36PYoD+BnaKWouI6bwxyZrZTH624rqzUVrsVO0yvBCya?= =?us-ascii?Q?8sMiVCEevcsZOifbh/ghkJf8DOwDDXZiJNRQclss1Fg5Y2xBc5xyXIyka6x+?= =?us-ascii?Q?D8V4e+fMCZ5b8wMKJx72et8oO5eJSr4R4UFeyztowNWWSBxQLeB4/7MvIYVp?= =?us-ascii?Q?KjWUJSiYq6eohswE1HA1hXybM1Zbg88+6v8cubjv3o8FZz73MGfX/gA7+0vM?= =?us-ascii?Q?zrX5rDyrRA6GzRFODu8S4mRdEgUHWFRYRKThjepJI9J+QsmN/b4YeKTKP+lP?= =?us-ascii?Q?tih4ESCvBg1LoWDt/jCH3Jfx4LMFYf0eoErTvYRIqYi1EIj79RukQePK6QlT?= =?us-ascii?Q?EZfvcU6qKacw3Ir9TMcnpnxHJar1YkdC0F7u4UD4A8amxa6nOhZWo2x5QziC?= =?us-ascii?Q?9z8R71NsvgBRbvGDVQbJaBFDz3H48e6YvHGF51R/HzpPRObKae0YtcAZ/+BJ?= =?us-ascii?Q?DY5ZDzyK5mW1AvXciBc7e0KiZnOgF1p6oF+OdDMb6FVAILBlX1eul4zmO9yO?= =?us-ascii?Q?wvjZC61xgffms4qRFsSmo8BgiHzSncGRrvJDGdqLxrXFFe9p01V2iO1CpQwz?= =?us-ascii?Q?qo5mN0bYykFij30DUBa50P55hVC+VXKUsnY5BI/pq/HpKRlz5pvxvvsU59Eu?= =?us-ascii?Q?ktBAWxnHERHC5lSyhjwSvg4VPRj9ImG7brgoSgtq8loBXUDrnuoIxTGRXhTy?= =?us-ascii?Q?HX/9CgodcWsrFzd5ceqmDBsSY5SpvLt7wjJnl6TOh8T797n5f3NeeEz3m4F2?= =?us-ascii?Q?Fm/Z4gXTPomxI3NNGF5hqJozhng8kAZez08HSUK1B+N0MnZ/p8H2KNMXbeuO?= =?us-ascii?Q?+QEpRLiJmWUNTb/tc8VDSMNYoMGkwO9WAJKhMrzxYe90Bmsm+On4tyS2GZF/?= =?us-ascii?Q?PEgURgGbFlYD6iI1PyVLI247t5dBYsyRp60mRO7nrMw/oVIzzaHnoZ/CBWuf?= =?us-ascii?Q?MbP1Uig1m8gXsvqYTvGnuwdieymx8aNzVifhwx3r+d4t6oXVYY3ps242L9zq?= =?us-ascii?Q?h0gXry3mIfBA3VsvzQdYekh4BIh0s9auWv6lsFS8hmbIZ9HXV9pL3yCMfDLD?= =?us-ascii?Q?v9+rFg=3D=3D?= X-Forefront-Antispam-Report: CIP:216.228.117.161;CTRY:US;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:mail.nvidia.com;PTR:dc6edge2.nvidia.com;CAT:NONE;SFS:(13230040)(36860700013)(1800799024)(82310400026)(7416014)(376014);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: f3MxfO3wpblQWefPER/4i+AUxI5uu8ByOrnTmJyBHbGyqMbCb4lWUnl4KP/cMXwndIgLkcs02/+mOe6rtG6nOOTGztOp786lA4oiOLINzS1tdgaxiDjy9iVN2BH0YXw6yQ6vk2jBSAYFC8yp/eZpFeTV9ZxyqFYptZabkUecIzm49SMcv9BjZOlbMU6Pe6dW73OxVgSomnD3vhPtvgdMifyzS8a+iDV9AdxGZDeP1PBy1gfU8lmBffj05nYAXhCP15VilaGMtwD47nrpRtYG7TxDSUJ2s88uzGlw0woXbZHmAsbNbzHjj8gyZX4/xcyNrX6vypJE+1cJaNd8fOpUTtERXQxp/CngHaeUT0mupRkugJCEB1YP3wijnFXAk2g2jqFc6IVS0MxUF1mnY3mTe7MIZkpK6TsYZ3hjGm32BaVYYFH2DN2eopaGjm6JZWbL X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 09 Feb 2026 09:44:40.4289 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 37d4d4d9-e388-46b0-a14c-08de67bfd8bb X-MS-Exchange-CrossTenant-Id: 43083d15-7273-40c1-b7db-39efd9ccc17a X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=43083d15-7273-40c1-b7db-39efd9ccc17a;Ip=[216.228.117.161];Helo=[mail.nvidia.com] X-MS-Exchange-CrossTenant-AuthSource: BY1PEPF0001AE1D.namprd04.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: DS7PR12MB6335 Jakub Kicinski writes: > Extend ynltool to compute HW GRO savings metric - how many > packets has HW GRO been able to save the kernel from seeing. > > Note that this definition does not actually take into account > whether the segments were or weren't eligible for HW GRO. > If a machine is receiving all-UDP traffic - new metric will show > HW-GRO savings of 0%. Conversely since the super-packet still > counts as a received packet, savings of 100% is not achievable. > Perfect HW-GRO on a machine with 4k MTU and 64kB super-frames > would show ~93.75% savings. With 1.5k MTU we may see up to > ~97.8% savings (if my math is right). > > Example after 10 sec of iperf on a freshly booted machine > with 1.5k MTU: > > $ ynltool qstats show > eth0 rx-packets: 40681280 rx-bytes: 61575208437 > rx-alloc-fail: 0 rx-hw-gro-packets: 1225133 > rx-hw-gro-wire-packets: 40656633 > $ ynltool qstats hw-gro > eth0: 96.9% savings > > None of the NICs I have access to can report "missed" HW-GRO > opportunities so computing a true "effectiveness" metric > is not possible. One could also argue that effectiveness metric > is inferior in environments where we control both senders and > receivers, the savings metrics will capture both regressions > in receiver's HW GRO effectiveness but also regressions in senders > sending smaller TSO trains. And we care about both. The main > downside is that it's hard to tell at a glance how well the NIC > is doing because the savings will be dependent on traffic patterns. > > Signed-off-by: Jakub Kicinski Reviewed-by: Petr Machata