This patchset add a new helper, bpf_for_each. One of the complexities of using for loops in bpf programs is that the verifier needs to ensure that in every possibility of the loop logic, the loop will always terminate. As such, there is a limit on how many iterations the loop can do. The bpf_for_each helper moves the loop logic into the kernel and can thereby guarantee that the loop will always terminate. The bpf_for_each helper simplifies a lot of the complexity the verifier needs to check, as well as removes the constraint on the number of loops able to be run. >From the test results, we see that using bpf_for_each in place of the traditional for loop led to a decrease in verification time and number of bpf instructions by 100%. The benchmark results show that as the number of iterations increases, the overhead per iteration decreases. The high-level overview of the patches - Patch 1 - kernel-side + API changes for adding bpf_for_each Patch 2 - tests Patch 3 - benchmark for overhead of a bpf_for_each call Joanne Koong (3): bpf: Add bpf_for_each helper selftests/bpf: Add tests for bpf_for_each selftest/bpf/benchs: add bpf_for_each benchmark include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 23 ++++ kernel/bpf/bpf_iter.c | 32 ++++++ kernel/bpf/helpers.c | 2 + kernel/bpf/verifier.c | 28 +++++ tools/include/uapi/linux/bpf.h | 23 ++++ tools/testing/selftests/bpf/Makefile | 3 +- tools/testing/selftests/bpf/bench.c | 4 + .../selftests/bpf/benchs/bench_for_each.c | 105 ++++++++++++++++++ .../bpf/benchs/run_bench_for_each.sh | 16 +++ .../bpf/prog_tests/bpf_verif_scale.c | 12 ++ .../selftests/bpf/prog_tests/for_each.c | 61 ++++++++++ .../selftests/bpf/progs/for_each_helper.c | 82 ++++++++++++++ tools/testing/selftests/bpf/progs/pyperf.h | 70 +++++++++++- .../selftests/bpf/progs/pyperf600_foreach.c | 5 + .../testing/selftests/bpf/progs/strobemeta.h | 73 +++++++++++- .../selftests/bpf/progs/strobemeta_foreach.c | 9 ++ 17 files changed, 544 insertions(+), 5 deletions(-) create mode 100644 tools/testing/selftests/bpf/benchs/bench_for_each.c create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_for_each.sh create mode 100644 tools/testing/selftests/bpf/progs/for_each_helper.c create mode 100644 tools/testing/selftests/bpf/progs/pyperf600_foreach.c create mode 100644 tools/testing/selftests/bpf/progs/strobemeta_foreach.c -- 2.30.2
