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X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: =?us-ascii?Q?xg+ksCL+s5yaAyU8FyQWcAlqYLx7EmBLVeyJL1HQjSLy5FkE86AXOHyTsTf+?= =?us-ascii?Q?/T2I/Xg7E8jhvUMRY9sJXTGpxGtvF1DC95W58OYjcjmH3XctQxBeN+iDYwvc?= =?us-ascii?Q?GlcEGlOxLfwUV8SOHx30TPaUCoTnLzDNr8uZ73Gh+DtBF49iVD5ik4NMcgMc?= =?us-ascii?Q?iwgfxzBbrGHNp/ZamFoeImq8rew2c51NH+ixQ0MOGrOjEYKHISRfHLzCrxQb?= =?us-ascii?Q?SoFcW2DX3PuHNSacWiEW1yJXdkg0Y0LK56UIJ+d1WeTM7hEUMgEUtKXwRR8V?= =?us-ascii?Q?ckEbNfy0qFDeUFJOWNthx1DpaKE6mQ1GwFGTeIigxkTbFyYT3rsjupKghxvt?= =?us-ascii?Q?731Cb6ZhXOKvX3c1V4tS0p7nzB94OKqmsB6FY9qMx21fYhtn9rmwOlMa+vtj?= =?us-ascii?Q?bWjDCiyKqkKZqXAGzyTEINis5JXC0yCeCnptkB4PiTtpzo5yoa+LWvNy/3qA?= =?us-ascii?Q?w3NhmgOwwkAi2YNJkko2elMh5Hzrlq1wDHXdZJ0Dt8H7Jlso/Lmt40sEq9Ie?= =?us-ascii?Q?ZSIqVMnOAXAKXzCxvWS4nSchmX0VG3jAMvynSsbAjWVqozRRLj2oRBI6B/UC?= =?us-ascii?Q?ktWJwjWGP7Y/TJ4Uf1bdIRwLvbd0BIwK/jUS7/9zSGeCYR+385qb8ILlmvPv?= =?us-ascii?Q?SuEbvg83SyMOSnOMB9rDB6hOwY/DxuPye7f+z07SPK58z6UWb359nL80677g?= =?us-ascii?Q?J15C+BZWpZegApie7basOm/bXGuufwp57WbD68h//ykuvPXh69ZA6AoT20cE?= =?us-ascii?Q?3SmkPg0DYal+/MxKyjCNKAngV4EUHci5MkfzMFSuaCs5LroslGErnr9GdNfo?= =?us-ascii?Q?z+OY0ePsqfR/rFtP0zNnk/yZRZ8ZNJ4tWkSovlah/s6CQGv4GgDj/tc5Vk+V?= =?us-ascii?Q?5EVkz7lOW31qUeFJHyzL9vA56AtD94qMndzehgmJoM9J1lLxsIUpyWq0QlUo?= =?us-ascii?Q?lop/mz+wGreOShkzY5OP2CaOjXGWegB5UcBP3BDdNhbIAMO2jMaJBtqIBsNF?= =?us-ascii?Q?Bf7y/KDtDkOitSchmjYfNqTXnMSm3xL2doOHGBdgl3FlEoCUit7kIzJV6dSJ?= =?us-ascii?Q?YgnZQGDsrgCxgx7i/7rhZSxwotSFwnuvh1Yq4XuLoA/FlFDktmRq03fyJhF/?= =?us-ascii?Q?kAR/2kWDYsNgVJ2f8qZhT5//+x9GCOkph6I1p2CEy2yCoiXy8kybgiu9EHqU?= =?us-ascii?Q?+4tG2ewyg12hrv/l5pu6fIY9s85xIP97/IlIlPZSiiXGbPdHeQJp9hFFJgAC?= =?us-ascii?Q?x9TCyPL4R2e73ZHWpj5nCPEna7nuEiDPh+rccfFP/bNY8BWtFuVu85x1khcp?= =?us-ascii?Q?MZCPw0g2yRahxWs50LCmmIABgBg4EuFICcp/9mSKe3sszg=3D=3D?= X-MS-Exchange-CrossTenant-Network-Message-Id: 6fdedc22-7590-43af-24c9-08d9675978ee X-MS-Exchange-CrossTenant-AuthSource: SA1PR15MB5016.namprd15.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 24 Aug 2021 23:47:03.0947 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 8ae927fe-1255-47a7-a2af-5f3a069daaa2 X-MS-Exchange-CrossTenant-MailboxType: HOSTED X-MS-Exchange-CrossTenant-UserPrincipalName: 1MsMNP+dcw9qugKq4d13eg5I9D7qQNr4eciISsLoorhuwJ3o+xAZFMPjBGyonEA2 X-MS-Exchange-Transport-CrossTenantHeadersStamped: SA0PR15MB3854 X-OriginatorOrg: fb.com X-Proofpoint-GUID: kKg0KMi16ByxD3b4_6mlJ26tf8wo-msr X-Proofpoint-ORIG-GUID: kKg0KMi16ByxD3b4_6mlJ26tf8wo-msr X-Proofpoint-UnRewURL: 1 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391,18.0.790 definitions=2021-08-24_07:2021-08-24,2021-08-24 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 malwarescore=0 suspectscore=0 impostorscore=0 adultscore=0 bulkscore=0 mlxscore=0 phishscore=0 priorityscore=1501 clxscore=1011 lowpriorityscore=0 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2107140000 definitions=main-2108240148 X-FB-Internal: deliver Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Fri, Aug 20, 2021 at 06:02:40PM -0700, Cong Wang wrote: > From: Cong Wang > > This *incomplete* patch introduces a programmable Qdisc with > eBPF. The goal is to make Qdisc as programmable as possible, > that is, to replace as many existing Qdisc's as we can. ;) > > The design was discussed during last LPC: > https://linuxplumbersconf.org/event/7/contributions/679/attachments/520/1188/sch_bpf.pdf > > Here is a summary of design decisions I made: > > 1. Avoid eBPF struct_ops, as it would be really hard to program > a Qdisc with this approach. Please explain more on this. What is currently missing to make qdisc in struct_ops possible? > 2. Avoid exposing skb's to user-space, which means we can't introduce > a map to store skb's. Instead, store them in kernel without exposure > to user-space. > > So I choose to use priority queues to store skb's inside a > flow and to store flows inside a Qdisc, and let eBPF programs > decide the *relative* position of the skb within the flow and the > *relative* order of the flows too, upon each enqueue and dequeue. > Each flow is also exposed to user as a TC class, like many other > classful Qdisc's. > > Although the biggest limitation is obviously that users can > not traverse the packets or flows inside the Qdisc, I think > at least they could store those global information of interest > inside their own map and map can be shared between enqueue and > dequeue. For example, users could use skb pointer as key and > rank as a value to find out the absolute order. > > One of the challeges is how to interact with existing TC infra, > for instance, if users install TC filters on this Qdisc, should > we respect this by ignoring or rejecting eBPF enqueue program > attached or vice versa? Should we allow users to replace each > priority queue of a class with a regular Qdisc? > > Any high-level feedbacks are welcome. Please do not review any > coding details until RFC tag is removed. > > Cc: Jamal Hadi Salim > Cc: Jiri Pirko > Signed-off-by: Cong Wang