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x-ms-exchange-antispam-messagedata: =?us-ascii?Q?ZyulpqsCfKeb1450f6XeON1PZstN9Fj/hPypKc2cBusX9XDZ/a3rvB3bNC01?= =?us-ascii?Q?VnO0pYf/qXopiK/7ZMys/7MExhOunHMN2nyhVajESEiE5q+LNLeXDBo4Ys1M?= =?us-ascii?Q?BQzgtOA7xsVJYjnnaj7XFExzqYbkLG+6pdhSjAdrbbIkSBzelBFPc6t/ybDn?= =?us-ascii?Q?Wp6TuFEWp51IrIKavmodpDzCwgeoN9I51qBjYEeYZDg7j8vRLHH+oR66i6Ol?= =?us-ascii?Q?BtXDsfArB3uHLVc6wWWqxx6RDT3f3iZXlQ3MmtborpsRX9xzm0sx2K4HTHz4?= =?us-ascii?Q?YtSzsJ2cYGu04DICVRQHim6jeEEacZsxyGIvNfSA8Kj7omWWyLEN4wjAq4Rg?= =?us-ascii?Q?gWHCJh731KYuo4sQ4zsnhEJKTbpmo61R6fdfihmhz33+HZ1Exj36TXe+2up+?= =?us-ascii?Q?XtfX4omUxkxjner8HvGHNltA6EuxH/cgTEUiFv+52sslya/gUfHRiKvo72Qg?= =?us-ascii?Q?rzka0rq1NKYZ9ZLBHSYJ2AuQiIvTWiGFVw/t6PVonAUKvpirBcUxSXCS0yis?= =?us-ascii?Q?5m80qeTq67Q5L41D/N5vc/MGXtCq3o8UmgBv1LvdHLszv6fBryXpZ85OC82k?= =?us-ascii?Q?dcKT9AxTw2bm16jrfVXkaQDPE4JHVe1wjoADlaSoauMm4DXkih+HLsHTOOPT?= =?us-ascii?Q?5OQc/iJA17HeAuShkdXZwqR6NrekM4MbGsi4pb2viG4EJg4uOyDUwgRk85sU?= =?us-ascii?Q?LGvW2ppG/QS81pqyNbaj5wpoEUwAQtG+d9YpJ79m/enT4kd+W0xFeD6sNawU?= =?us-ascii?Q?CKd+pc0n9Y5y26yVkmLSSOO3O1OOye3iBqpmVfNf/WKnx5HROqKHBRiL4bCN?= =?us-ascii?Q?48PFihzfFyG1EclSJufsxafjFtVEA0HjotfTUmOp2ON7nmKhZT/flrU1LdF4?= =?us-ascii?Q?KGnPjnsjAFpsSJieO5uMMop3EdLdLq15ZfcDv1XA6revkJvsJphtm8GJJ0Yb?= =?us-ascii?Q?DG2oV/A6x4SppJl1sYdDkh6EO2rQwuvyNAnuMZ7KdGRtEu7fSZuxPepUPP7Y?= =?us-ascii?Q?8ajn?= Content-Type: text/plain; charset="us-ascii" Content-ID: <7FCE58176DE30A40904ACDF1D08D270B@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: VI1PR04MB5696.eurprd04.prod.outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 1c02e29c-a37a-4286-0142-08d89b0592ae X-MS-Exchange-CrossTenant-originalarrivaltime: 07 Dec 2020 23:12:31.0214 (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: sIASoWE/95+Fj8ip88jx/4MqB+i6pM2FbzBRlMF/n1A5yfl37IqUzV47xDVbEtx6XauVUXbHQUYpt/sKagBCpw== X-MS-Exchange-Transport-CrossTenantHeadersStamped: VI1PR0401MB2511 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Dec 07, 2020 at 02:49:35PM -0800, Vinicius Costa Gomes wrote: > Jakub Kicinski writes: > > > On Tue, 1 Dec 2020 20:53:16 -0800 Vinicius Costa Gomes wrote: > >> $ tc qdisc replace dev $IFACE parent root handle 100 taprio \ > >> num_tc 3 \ > >> map 2 2 1 0 2 2 2 2 2 2 2 2 2 2 2 2 \ > >> queues 1@0 1@1 2@2 \ > >> base-time $BASE_TIME \ > >> sched-entry S 0f 10000000 \ > >> preempt 1110 \ > >> flags 0x2 > >> > >> The "preempt" parameter is the only difference, it configures which > >> queues are marked as preemptible, in this example, queue 0 is marked > >> as "not preemptible", so it is express, the rest of the four queues > >> are preemptible. > > > > Does it make more sense for the individual queues to be preemptible > > or not, or is it better controlled at traffic class level? > > I was looking at patch 2, and 32 queues isn't that many these days.. > > We either need a larger type there or configure this based on classes. > > I can set more future proof sizes for expressing the queues, sure, but > the issue, I think, is that frame preemption has dimishing returns with > link speed: at 2.5G the latency improvements are on the order of single > digit microseconds. At greater speeds the improvements are even less > noticeable. You could look at it another way. You can enable jumbo frames in your network, and your latency-sensitive traffic would not suffer as long as the jumbo frames are preemptible. > The only adapters that I see that support frame preemtion have 8 queues > or less. > > The idea of configuring frame preemption based on classes is > interesting. I will play with it, and see how it looks. I admit I never understood why you insist on configuring TSN offloads per hardware queue and not per traffic class.=