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Miller" , Paolo Abeni , Eric Dumazet , Claudiu Manoil , Vinicius Costa Gomes , Michael Walle , Xiaoliang Yang , Po Liu Subject: Re: [PATCH net-next 2/2] net: enetc: count the tc-taprio window drops Thread-Topic: [PATCH net-next 2/2] net: enetc: count the tc-taprio window drops Thread-Index: AQHYZIwYAyud9yi3kkettoRjyMxmN60aQ40AgAAIaIA= Date: Wed, 11 May 2022 22:57:46 +0000 Message-ID: <20220511225745.xgrhiaghckrcxdaj@skbuf> References: <20220510163615.6096-1-vladimir.oltean@nxp.com> <20220510163615.6096-3-vladimir.oltean@nxp.com> <20220511152740.63883ddf@kernel.org> In-Reply-To: <20220511152740.63883ddf@kernel.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: authentication-results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=nxp.com; x-ms-publictraffictype: Email x-ms-office365-filtering-correlation-id: 1d1fecf5-fae8-482d-8229-08da33a1aa38 x-ms-traffictypediagnostic: PAXPR04MB9399:EE_ x-microsoft-antispam-prvs: x-ms-exchange-senderadcheck: 1 x-ms-exchange-antispam-relay: 0 x-microsoft-antispam: BCL:0; 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charset="us-ascii" Content-ID: <868F10FA5FF9A34AB7AE80290D5DC870@eurprd04.prod.outlook.com> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 X-OriginatorOrg: nxp.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-AuthSource: VI1PR04MB5136.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1d1fecf5-fae8-482d-8229-08da33a1aa38 X-MS-Exchange-CrossTenant-originalarrivaltime: 11 May 2022 22:57:46.4459 (UTC) X-MS-Exchange-CrossTenant-fromentityheader: Hosted X-MS-Exchange-CrossTenant-id: 686ea1d3-bc2b-4c6f-a92c-d99c5c301635 X-MS-Exchange-CrossTenant-mailboxtype: HOSTED X-MS-Exchange-CrossTenant-userprincipalname: Bw8up7qmy1ZasW4s1iADQ5JppNkHJXCFrFtj7+Cc+KztkTA3/D+TlT7tQkacc2bRI3aDQyovRBiUI0+Ug2ZOfQ== X-MS-Exchange-Transport-CrossTenantHeadersStamped: PAXPR04MB9399 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Wed, May 11, 2022 at 03:27:40PM -0700, Jakub Kicinski wrote: > On Tue, 10 May 2022 19:36:15 +0300 Vladimir Oltean wrote: > > From: Po Liu > >=20 > > The enetc scheduler for IEEE 802.1Qbv has 2 options (depending on > > PTGCR[TG_DROP_DISABLE]) when we attempt to send an oversized packet > > which will never fit in its allotted time slot for its traffic class: > > either block the entire port due to head-of-line blocking, or drop the > > packet and set a bit in the writeback format of the transmit buffer > > descriptor, allowing other packets to be sent. > >=20 > > We obviously choose the second option in the driver, but we do not > > detect the drop condition, so from the perspective of the network stack= , > > the packet is sent and no error counter is incremented. > >=20 > > This change checks the writeback of the TX BD when tc-taprio is enabled= , > > and increments a specific ethtool statistics counter and a generic > > "tx_dropped" counter in ndo_get_stats64. >=20 > Is there no MIB attribute in the standard for such drops? >=20 > The semantics seem petty implementation-independent can we put it into > some structured ethtool stats instead? My copy of IEEE 802.1Q-2018 talks about the following MIB table entries in clause 17.2.22 Structure of the IEEE8021-ST-MIB: ieee8021STMaxSDU subtree ieee8021STMaxSDUTable ieee8021STTrafficClass ieee8021STMaxSDU ieee8021TransmissionOverrun ieee8021STParameters ieee8021STParametersTable ieee8021STGateEnabled ieee8021STAdminGateStates ieee8021STOperGateStates ieee8021STAdminControlListLength ieee8021STOperControlListLength ieee8021STAdminControlList ieee8021STOperControlList ieee8021STAdminCycleTimeNumerator ieee8021STAdminCycleTimeDenominator ieee8021STOperCycleTimeNumerator ieee8021STOperCycleTimeDenominator ieee8021STAdminCycleTimeExtension ieee8021STOperCycleTimeExtension ieee8021STAdminBaseTime ieee8021STOperBaseTime ieee8021STConfigChange ieee8021STConfigChangeTime ieee8021STTickGranularity ieee8021STCurrentTime ieee802STConfigPending ieee8021STSupportedListMax The only entry that is a counter in the Scheduled Traffic MIB is Transmissi= onOverrun, but that isn't what this is. Instead, this would be a TransmissionOverrunAv= oidedByDropping, for which there appears to be no standardization.=