This patchset is a proposal of how the Traffic Control subsystem can be used to offload the configuration of the Credit Based Shaper (defined in the IEEE 802.1Q-2014 Section 8.6.8.2) into supported network devices.
As part of this work, we've assessed previous public discussions related to TSN enabling: patches from Henrik Austad (Cisco), the presentation from Eric Mann at Linux Plumbers 2012, patches from Gangfeng Huang (National Instruments) and the current state of the OpenAVNU project (https://github.com/AVnu/OpenAvnu/). Overview ======== Time-sensitive Networking (TSN) is a set of standards that aim to address resources availability for providing bandwidth reservation and bounded latency on Ethernet based LANs. The proposal described here aims to cover mainly what is needed to enable the following standards: 802.1Qat and 802.1Qav. The initial target of this work is the Intel i210 NIC, but other controllers' datasheet were also taken into account, like the Renesas RZ/A1H RZ/A1M group and the Synopsis DesignWare Ethernet QoS controller. Proposal ======== Feature-wise, what is covered here is the configuration interfaces for HW implementations of the Credit-Based shaper (CBS, 802.1Qav). CBS is a per-queue shaper. Given that this feature is related to traffic shaping, and that the traffic control subsystem already provides a queueing discipline that offloads config into the device driver (i.e. mqprio), designing a new qdisc for the specific purpose of offloading the config for the CBS shaper seemed like a good fit. For steering traffic into the correct queues, we use the socket option SO_PRIORITY and then a mechanism to map priority to traffic classes / Tx queues. The qdisc mqprio is currently used in our tests. As for the CBS config interface, this patchset is proposing a new qdisc called 'cbs'. Its 'tc' cmd line is: $ tc qdisc add dev IFACE parent ID cbs locredit N hicredit M sendslope S \ idleslope I Note that the parameters for this qdisc are the ones defined by the 802.1Q-2014 spec, so no hardware specific functionality is exposed here. Per-stream shaping, as defined by IEEE 802.1Q-2014 Section 34.6.1, is not yet covered by this proposal. The following are changes since commit 3fc27b71b894f5e2ad611297d5817b6092c96626: tools: bpftool: try to mount bpffs if required for pinning objects and are available in the git repository at: git://git.kernel.org/pub/scm/linux/kernel/git/jkirsher/next-queue 1GbE Andre Guedes (1): igb: Add support for CBS offload Jesus Sanchez-Palencia (3): net/sched: Check for null dev_queue on create flow net/sched: Change behavior of mq select_queue() net/sched: Add select_queue() class_ops for mqprio Vinicius Costa Gomes (3): net/sched: Introduce Credit Based Shaper (CBS) qdisc net/sched: Add support for HW offloading for CBS net/sched/sch_cbs: Fix compilation on 32bit architectures drivers/net/ethernet/intel/igb/e1000_defines.h | 23 ++ drivers/net/ethernet/intel/igb/e1000_regs.h | 8 + drivers/net/ethernet/intel/igb/igb.h | 6 + drivers/net/ethernet/intel/igb/igb_main.c | 347 +++++++++++++++++++++++ include/linux/netdevice.h | 1 + include/net/pkt_sched.h | 9 + include/uapi/linux/pkt_sched.h | 19 ++ net/sched/Kconfig | 11 + net/sched/Makefile | 1 + net/sched/sch_cbs.c | 373 +++++++++++++++++++++++++ net/sched/sch_generic.c | 8 +- net/sched/sch_mq.c | 10 +- net/sched/sch_mqprio.c | 7 + 13 files changed, 813 insertions(+), 10 deletions(-) create mode 100644 net/sched/sch_cbs.c -- 2.14.2
