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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , xfr@outlook.com, "linux-tegra@vger.kernel.org" References: <20250124003501.5fff00bc@orangepi5-plus> <20250124104256.00007d23@gmail.com> <20250125230347.0000187b@gmail.com> From: Jon Hunter Content-Language: en-US In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-ClientProxiedBy: LO0P123CA0012.GBRP123.PROD.OUTLOOK.COM (2603:10a6:600:354::20) To SJ2PR12MB8784.namprd12.prod.outlook.com (2603:10b6:a03:4d0::11) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: SJ2PR12MB8784:EE_|MN0PR12MB5859:EE_ X-MS-Office365-Filtering-Correlation-Id: 49ddc7b1-f3aa-4b44-445b-08dd40747848 X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0;ARA:13230040|1800799024|376014|7416014|366016; X-Microsoft-Antispam-Message-Info: =?utf-8?B?aFNKM3JnY1lZME9qajhOZ1VFalZZbVdncXplVmRXd0t0eklJNlgwSGwrQ05l?= =?utf-8?B?OThtYmhtcGxSd0hKeWRHV2ZSNmxEbTNnVUIzdVlXWHp0b01kMDVRL1Jod1Za?= =?utf-8?B?d3hjV3R1RnhDVjhWbk5OWVUrRGt5YzBMMy9KYmVyUGtoOTJ3eGlKQlVBY3lm?= =?utf-8?B?QVM1dlU1Uk05akRQYWdTS0l2TkZQRUpmK0NGeGoraVFXK0R0bTI5b2VFbko5?= =?utf-8?B?aXJ3WVBkZnpNYi9JNjA3dWYxS2xoNmw5KzQyZWNCSjFtdVBqa2Rjb2hxL1FV?= =?utf-8?B?a0xjZkZUaW1FTU5MYVpkSC9uUTJNRUF5a2tSaEdGaVpHN1g3eXFhM2cyWDB3?= =?utf-8?B?NG5uL0ovTkJPSXN0K3NHdGxONjZtbVp3Y0kvZ3VUdUJsUU93cDFFMDFTSUI3?= =?utf-8?B?RjY3bjNxd0FHbHlkV3N0akRIM3dVRzIrTEJ0RGRUUW1aMVFZM1VpbEFBdUlx?= =?utf-8?B?Q2ExWkVjZXl5MHBFdjhyZ3JkWjVwV0JRdXJpdjJQQ0dLQWVLK0JjUHFoTjhC?= =?utf-8?B?Ymhkc2t4c1A2MWdHUTUvNnhYSm5UQ0Fjd0RBSUVYUDlidEVvNzBqdko5TGR1?= =?utf-8?B?K0xMUm1TM2NXWUZtYlRLczNtMDdqcFJuWkhDb0hvazJNVXE4TU1YRCtmL00z?= =?utf-8?B?emUzY0c5M2JNMVJyeWV0QkpVZnl0NWVvbjByWkljazlIWEw3SUFUcFJNVkp5?= =?utf-8?B?aU12d01IblRpaDY2bEh4c1kySmVJTmVPRTJmMWd6WUo2MXJDZnE2WWFuWWl3?= =?utf-8?B?NTJVeWxNRHozUkhnMDB6Yno3SlhNTlF5aCs4TnBObXdxNmN2bnhBOWZnaHUv?= =?utf-8?B?eitpSERCckhUcGRxVTU3T1RldGNjNm43M1krYmV5M1VuRWptWFhmckJyWCsz?= =?utf-8?B?bCtEWnlVQ0hBdzIrQVVneFRDekJ5SFB5Q0Z0MG1yMDRmVmRPTlM2OXBpL1ZI?= =?utf-8?B?eU95dmNvVFFOclZhMHZ1RG5LQjZFellnaFlmcmxtNU9SWFRxT0dYNWxYWWY5?= =?utf-8?B?VE44VkxpS1JiY1lLSWRlMnowMnVBUkJZZnhmQUZBLzZmYUV0VTZrZTJUQkZt?= =?utf-8?B?b3NFZVpIQkJ6R2dFZTI4ZXFFakZuRUkzVWwyOWNXR1g3ZC9YTFp2MjBmOEJY?= =?utf-8?B?WkJVZVh0Z0hUYnZvR3lFVnN6ZzBOYVdQNmszaVNQSG5BSG5mcWZWTStYdTZG?= =?utf-8?B?enpPNXdZc3VGbFh2UFo0aVlFNTFEQzBwV3BDTk1Fbm9CUVQ0dTdZelZUOEVF?= =?utf-8?B?cUlITDdMR2w1UEtUdzd1bDdTOVdzZGF1ek1KUTFMR2ZBUkNycXNmWjVKTllV?= =?utf-8?B?bk4yMXFoMDgwcXpyNlcxdlFjS2dYbUdTL0JwUUhHZXkrLzhZY1ZKdnBpaDQv?= =?utf-8?B?S09RUVROZnRmZ2k4MGF2NWNnMmxwUFNqcGdDZEVXU2R0TjVadUgxQ3J1WmEz?= =?utf-8?B?WGRtMUFPeGNIeHpXTjFhc1duZmNXN3J6OEtRVXJRTDlieHdCNDFXWC9qWFhX?= =?utf-8?B?S1N4TFhCcDFEcE1MVk83YUFwKzdtMTNjdzFzWmlGOGxCUUh4TjI5dDRmdDVZ?= =?utf-8?B?cWx5eUttSCsrMGZwQ1B1SXM0aHVNcnBoKzRRTnY0aDZ6cnp0OFdEM0h4Ukhw?= =?utf-8?B?cHNTNzAvc2dLb1ladEcrWGJqWHo0bmk2OVpySWd1UHpSNjVyUzQ3bENqNmh5?= =?utf-8?B?RE9pSTdrZFdVMkw4bjJZSCt4K1VwUFZoMVJLVDA5dVJTR0t6bHBxdVFkLytk?= =?utf-8?B?bHZBNFNpblBVblNwdDJJWm9Ycmk5NHNiblhVVjVka3E2Uk5LdDcyUEJyc1RD?= =?utf-8?B?dEQrYTQvMm56MzRzM1RicmdNREphWmRvQjBibFdoVzMrL3NxM2Vpb2FZVXB6?= =?utf-8?Q?0tTlvBaX/PBP0?= X-Forefront-Antispam-Report: CIP:255.255.255.255;CTRY:;LANG:en;SCL:1;SRV:;IPV:NLI;SFV:NSPM;H:SJ2PR12MB8784.namprd12.prod.outlook.com;PTR:;CAT:NONE;SFS:(13230040)(1800799024)(376014)(7416014)(366016);DIR:OUT;SFP:1101; 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It was only for diagnostic purposes, >>>>>> i.e. to see if there is some kind of cache coherence issue, >>>>>> which seems to be the case? So perhaps the only fix needed is >>>>>> to add dma-coherent to our device tree? >>>>> >>>>> That sounds quite error prone. How many other DT blobs are >>>>> missing the property? If the memory should be coherent, i would >>>>> expect the driver to allocate coherent memory. Or the driver >>>>> needs to handle non-coherent memory and add the necessary >>>>> flush/invalidates etc. >>>> >>>> stmmac driver does the necessary cache flush/invalidates to >>>> maintain cache lines explicitly. >>> >>> Given the problem happens when the kernel performs syncing, is it >>> possible that there is a problem with how the syncing is performed? >>> >>> I am not familiar with this driver, but it seems to allocate multiple >>> buffers per packet when split header is enabled and these buffers are >>> allocated from the same page pool (see stmmac_init_rx_buffers()). >>> Despite that, the driver is creating the page pool with a non-zero >>> offset (see __alloc_dma_rx_desc_resources()) to avoid syncing the >>> headroom, which is only present in the head buffer. >>> >>> I asked Thierry to test the following patch [1] and initial testing >>> seems OK. He also confirmed that "SPH feature enabled" shows up in the >>> kernel log. >> >> It is recommended to disable the "SPH feature" by default unless some >> certain cases depend on it. Like Ido said, two large buffers being >> allocated from the same page pool for each packet, this is a huge waste >> of memory, and brings performance drops for most of general cases. >> >> Our downstream driver and two mainline drivers disable SPH by default: >> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/drivers/net/ethernet/stmicro/stmmac/dwmac-dwc-qos-eth.c#n357 >> https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/tree/drivers/net/ethernet/stmicro/stmmac/dwmac-intel.c#n471 > > Okay, that's something we can look into changing. What would be an > example of a use-case depending on SPH? Also, isn't this something > that should be a policy that users can configure? > > Irrespective of that we should fix the problems we are seeing with > SPH enabled. Any update on this? Thanks Jon -- nvpublic