For network stack, RPS, namely Receive Packet Steering, is used to distribute network protocol processing from hardware-interrupted CPU to specific CPUs and alleviating soft-irq load of the interrupted CPU. For block layer, soft-irq (for single queue device) or hard-irq (for multiple queue device) is used to handle IO completion, so RPS will be useful when the soft-irq load or the hard-irq load of a specific CPU is too high, or a specific CPU set is required to handle IO completion. Instead of setting the CPU set used for handling IO completion through sysfs or procfs, we can attach an eBPF program to the request-queue, provide some useful info (e.g., the CPU which submits the request) to the program, and let the program decides the proper CPU for IO completion handling. In order to demonostrate the effect of IO completion redirection, a test programm is built to redirect the IO completion handling to all online CPUs or a specific CPU set: ./test_blkdev_ccpu -d /dev/vda or ./test_blkdev_ccpu -d /dev/nvme0n1 -s 4,8,10-13 However I am still trying to find out a killer scenario for the eBPF redirection, so suggestions and comments are welcome. Regards, Tao Hou Tao (2): block: add support for redirecting IO completion through eBPF selftests/bpf: add test program for redirecting IO completion CPU block/Makefile | 2 +- block/blk-bpf.c | 127 +++++++++ block/blk-mq.c | 22 +- block/blk-softirq.c | 27 +- include/linux/blkdev.h | 3 + include/linux/bpf_blkdev.h | 9 + include/linux/bpf_types.h | 1 + include/uapi/linux/bpf.h | 2 + kernel/bpf/syscall.c | 9 + tools/include/uapi/linux/bpf.h | 2 + tools/lib/bpf/libbpf.c | 1 + tools/lib/bpf/libbpf_probes.c | 1 + tools/testing/selftests/bpf/Makefile | 1 + .../selftests/bpf/progs/blkdev_ccpu_rr.c | 66 +++++ .../testing/selftests/bpf/test_blkdev_ccpu.c | 246 ++++++++++++++++++ 15 files changed, 507 insertions(+), 12 deletions(-) create mode 100644 block/blk-bpf.c create mode 100644 include/linux/bpf_blkdev.h create mode 100644 tools/testing/selftests/bpf/progs/blkdev_ccpu_rr.c create mode 100644 tools/testing/selftests/bpf/test_blkdev_ccpu.c -- 2.22.0
