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emacs 30.2 From: Petr Machata To: Jakub Kicinski CC: , , , , , , , , , , , , Subject: Re: [PATCH net-next 6/9] selftests: drv-net: gro: use SO_TXTIME to schedule packets together Date: Fri, 6 Feb 2026 16:19:26 +0100 In-Reply-To: <20260205220541.2992807-7-kuba@kernel.org> Message-ID: <878qd5292w.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: SJ1PEPF00001CE0:EE_|IA0PR12MB8837:EE_ X-MS-Office365-Filtering-Correlation-Id: 2cb51b15-98a8-450b-655a-08de6593370e X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|376014|7416014|36860700013|82310400026|1800799024; X-Microsoft-Antispam-Message-Info: =?us-ascii?Q?88HiN1LBzhLMtZqX+Uu9posWtpprFv/42LxMo/W19LcEPccTct0MdHUBpg8S?= =?us-ascii?Q?1nE56Y3941DVhBpMxSIBlpy0mr+BHNvqV3WXgjsyb/1WV9dzgRPKowxrJUoT?= =?us-ascii?Q?bMSnj0wSdQ0R4cYYkWiF+XZNvyoKFHpn7zNXY+4FdSvIk54STS2zdfpcKLq4?= =?us-ascii?Q?sm5wOBBkN2moHFjY4qAmiDm8XqXD2ZqWE58jo0ZZ8ctajSDgGts/HGDowcbh?= =?us-ascii?Q?zhiEmiCGwjSLI7T/+xKqZ/em6iTzldr0SSx0mz4YWOuQaUivy+w+2Kch9DAm?= =?us-ascii?Q?Cf/K5a4U+rL6A+ES9aKtIytPcJsJ0543qArVhjp1SbE/RntObyM/uGarA1hN?= =?us-ascii?Q?oClp1kyOqQT5vCJ5mY5qIzhjFJzHHTGL/L76OmbJrA2/Rjxak6wOwR+IB3ja?= =?us-ascii?Q?2YpLLLZGnYPtamJ/uU++x7HG7hnhB0AGIoGPlh/oTCcGTpRyT/S86dJ4K2tZ?= =?us-ascii?Q?pGAXDvozhhUg1v/QOCW5v+CFSJwV4G70Bws7E+B33lVqPcs97bNagh45F4FY?= =?us-ascii?Q?vLW+I9zz8+ZdSyQO5lP6mH2Z90AZE2nepxCRQd9iCrhKq9QX/Wco9DZh5BJL?= =?us-ascii?Q?PpzIfVvvNWmQ+cIB547bMYA1yBUp9/76Nm9di+ipz26+0SNJDph+IfcrKxd0?= =?us-ascii?Q?+s8ptS2kMdEzzkOWgx2IWYxyZqjKBxtvBP5QazJqYiRhEJFJj743KZAcfK8u?= =?us-ascii?Q?c59Xex9UW9wbj7RqwyTllk2FYSFV1PVkSNG10BLlB8WU1F9o1m3fNcemLqLg?= =?us-ascii?Q?0KBAxHX8hIImeOMrDCP3ecK/5kuRWq8xHyDmiPHQqy4NO9NDN5tFzLgrY9BZ?= =?us-ascii?Q?gXzH6Oa10lxI5NsJ0t9v9gKF/nCHxxQDtRPw7PXdgftHojAWXwKIfbiuSm/P?= =?us-ascii?Q?h6oBu89Oa3Vv9LbYhSqoKl1S1bw5YhGmI0L+3s19blGNdt7WTb6Hm+J/H4x8?= =?us-ascii?Q?fvyfs+iSHr82ef08obBMN1851ISPrRf2acSnZuRAdOnTfMkJzgkjorFUBt2A?= =?us-ascii?Q?POZxCl9vJt7BVPJckXKi9YSVZDVQuIN7+z/wBroAGOnKfkwGZmKiGEC8xmIp?= =?us-ascii?Q?QPqNEy8bD0OpjQrRwinOcei7wqW5MYYZkHqDaUyeE/nszUlfSVrePw47AF+L?= =?us-ascii?Q?M+2lBt9tC7lYjiWnCkTnMjtJ9QSU8UFDPxwq+Jid+QMCE1xx+N83CuKHSamJ?= =?us-ascii?Q?9ep47J4mXLNX3bjj9AukDWSNWUcvMdvsIBj87w2DV3nCVIQuCebJuw3LmJWs?= =?us-ascii?Q?IBqXKFo4Qc1vO7AMP9T2AVyq8hP6Yo0zDIkmc0FoD1a2BXptLxnx/3B1YtPx?= =?us-ascii?Q?cSxT3pRJ4L8QOYvNVNccijErVyJtx4ueJaCH+JdAtEIkBrbi11QD9J4SMmVS?= =?us-ascii?Q?VX8pbBf8LnkeQcBuupGghj3NsaOTQ0oXVYswTlK5pBefc7knZPt+oH/iu5uu?= =?us-ascii?Q?1EbguTpaa+FwXjK0brihfP7PMA2P2+65HFj1H4kaN5GDejDbFnRphXBoduep?= =?us-ascii?Q?3c1relDOVeKZVJKg/e/nFE2B9IB119wKb0H6ARWxRnaIEq/6+nZEREru2Pto?= =?us-ascii?Q?EgNyR4T2vQ+zZsWXIkVjGPjxVEb5BN+rrbB2wmCCnxoS7uiAKurChr5JZBt3?= =?us-ascii?Q?xivslnIxkACqkcP+GSDlyuT7jP81wyl6125B2UZLPAxP1Vb2BdwrEooR+/b/?= =?us-ascii?Q?BWH4Og=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)(376014)(7416014)(36860700013)(82310400026)(1800799024);DIR:OUT;SFP:1101; X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: juQwm2WZo/tEJf1QYWJwKn3j3LwqoX6vCF0yEITB5dmtmsCTNOnK0bH2ZxHLmDWTpxwEPdQgImmk1QgfYYqNvRNSUTnT3XBrLn4lcU8rk02rHAXe8ktJ4KJSjagMxR/1yZsNsCZWaR1ZwQvNyxLHfTcY0hffBU0mOOXVowjAmiXdghm1q9bjH5u9/NfPPqdgRbC8b50A8ZcNTm8U8IckaD+D1F/NQC0kID2vf64+2PbO4ErOj5G3dBSjh7+9gMHLfaGNRS2BcqQKYKYoQnnCqveP95D7jnJmoKhF+QDBOpZqLblhJPYVcRCo/yUfG7EjUGSkfG+46pxt+BH7ly/u7dUdy7uGRMcSoKSvMcOlGWyjcrepU6W41JlsR0bSs40/Cq1YAOunZzMsQdW+GylYsgXrn3Up4BVxCtpdf/iYexitO6KNSJoeyjrOAado2C8a X-OriginatorOrg: Nvidia.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 06 Feb 2026 15:20:09.1122 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 2cb51b15-98a8-450b-655a-08de6593370e 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: SJ1PEPF00001CE0.namprd05.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: IA0PR12MB8837 Jakub Kicinski writes: > Longer packet sequence tests are quite flaky when the test is run > over a real network. Try to avoid at least the jitter on the sender > side by scheduling all the packets to be sent at once using SO_TXTIME. > Use hardcoded tx time of 5msec in the future. In my test increasing > this time past 2msec makes no difference so 5msec is plenty of margin. > Since we now expect more output buffering make sure to raise SNDBUF. > > Experimenting with long sequences I see frequent failures when sending > 200 packets, only 50-100 packets get coalesced. With this change > up to 1000 packets get coalesced relatively reliably. > > Signed-off-by: Jakub Kicinski Reviewed-by: Petr Machata