This patchset is a proposal that adds zero copy network Rx to io_uring. With it, userspace can register a region of host memory for receiving data directly from a NIC using DMA, without needing a kernel to user copy. This is still a WIP and has a list of known issues. We're looking for feedback on the overall approach. Full kernel tree including some out of tree BNXT changes: https://github.com/spikeh/linux/tree/zcrx On the userspace side, support is added to both liburing and Netbench: https://github.com/spikeh/liburing/tree/zcrx2 https://github.com/spikeh/netbench/tree/zcrx Hardware support is added to the Broadcom BNXT driver. This patchset + userspace code was tested on an Intel Xeon Platinum 8321HC CPU and Broadcom BCM57504 NIC. Early benchmarks using this prototype, with iperf3 as a load generator, showed a ~50% reduction in overall system memory bandwidth as measured using perf counters. Note that DDIO must be disabled on Intel systems. Build Netbench using the modified liburing above. This patchset is based on the work by Jonathan Lemon <jonathan.lemon@xxxxxxxxx>: https://lore.kernel.org/io-uring/20221108050521.3198458-1-jonathan.lemon@xxxxxxxxx/ Changes in RFC v4: ------------------ * Rebased on top of Mina Almasry's TCP devmem patchset and latest net-next, now sharing common infra e.g.: * netmem_t and net_iovs * Page pool memory provider * The registered buffer (rbuf) completion queue where completions from io_recvzc requests are posted is removed. Now these post into the main completion queue, using big (32-byte) CQEs. The first 16 bytes is an ordinary CQE, while the latter 16 bytes contain the io_uring_rbuf_cqe as before. This vastly simplifies the uAPI and removes a level of indirection in userspace when looking for payloads. * The rbuf refill queue is still needed for userspace to return buffers to kernel. * Simplified code and uAPI on the io_uring side, particularly io_recvzc() and io_zc_rx_recv(). Many unnecessary lines were removed e.g. extra msg flags, readlen, etc. Changes in RFC v3: ------------------ * Rebased on top of Jakub Kicinski's memory provider API RFC. The ZC pool added is now a backend for memory provider. * We're also reusing ppiov infrastructure. The refcounting rules stay the same but it's shifted into ppiov->refcount. That lets us to flexibly manage buffer lifetimes without adding any extra code to the common networking paths. It'd also make it easier to support dmabufs and device memory in the future. * io_uring also knows about pages, and so ppiovs might unnecessarily break tools inspecting data, that can easily be solved later. Many patches are not for upstream as they depend on work in progress, namely from Mina: * struct netmem_t * Driver ndo commands for Rx queue configs * struct page_pool_iov and shared pp infra Changes in RFC v2: ------------------ * Added copy fallback support if userspace memory allocated for ZC Rx runs out, or if header splitting or flow steering fails. * Added veth support for ZC Rx, for testing and demonstration. We will need to figure out what driver would be best for such testing functionality in the future. Perhaps netdevsim? * Added socket registration API to io_uring to associate specific sockets with ifqs/Rx queues for ZC. * Added multi-socket support, such that multiple connections can be steered into the same hardware Rx queue. * Added Netbench server/client support. Known deficiencies that we will address in a future patchset: * Proper test driver + selftests, maybe netdevsim. * Revisiting userspace API. * Multi-region support. * Steering setup. * Further optimisation work. * ...and more. If you would like to try out this patchset, build and run the kernel tree then build Netbench using liburing, all from forks above. Run setup.sh first: https://gist.github.com/isilence/e6a28ce41a545a261566672104afa461 Then run the following commands: sudo ip netns exec nsserv ./netbench --server_only 1 --v6 false \ --rx "io_uring --provide_buffers 0 --use_zc 1 \ --zc_pool_pages 16384 --zc_ifname ptp-serv" --use_port 9999 sudo ip netns exec nscl ./netbench --client_only 1 --v6 false \ --tx "epoll --threads 1 --per_thread 1 --size 2800" \ --host 10.10.10.20 --use_port 9999 David Wei (7): io_uring: introduce interface queue io_uring: add mmap support for shared ifq ringbuffers netdev: add XDP_SETUP_ZC_RX command io_uring: setup ZC for an Rx queue when registering an ifq io_uring: add zero copy buf representation and pool io_uring: add io_recvzc request io_uring/zcrx: add copy fallback Pavel Begunkov (9): net: generalise pp provider params passing io_uring: delayed cqe commit net: page_pool: add ->scrub mem provider callback io_uring: separate header for exported net bits io_uring/zcrx: implement socket registration io_uring: implement pp memory provider for zc rx io_uring/zcrx: implement PP_FLAG_DMA_* handling net: execute custom callback from napi veth: add support for io_uring zc rx drivers/net/veth.c | 214 +++++++- include/linux/io_uring.h | 6 - include/linux/io_uring/net.h | 30 ++ include/linux/io_uring_types.h | 5 + include/linux/net.h | 2 + include/linux/netdevice.h | 6 + include/net/busy_poll.h | 7 + include/net/netdev_rx_queue.h | 3 + include/net/page_pool/types.h | 2 + include/uapi/linux/io_uring.h | 50 ++ io_uring/Makefile | 3 +- io_uring/io_uring.c | 15 +- io_uring/io_uring.h | 10 + io_uring/net.c | 108 +++- io_uring/opdef.c | 16 + io_uring/register.c | 13 + io_uring/uring_cmd.c | 1 + io_uring/zc_rx.c | 916 +++++++++++++++++++++++++++++++++ io_uring/zc_rx.h | 83 +++ net/core/dev.c | 48 +- net/core/page_pool.c | 8 +- net/socket.c | 3 +- 22 files changed, 1530 insertions(+), 19 deletions(-) create mode 100644 include/linux/io_uring/net.h create mode 100644 io_uring/zc_rx.c create mode 100644 io_uring/zc_rx.h -- 2.43.0
