Hi, The motivation for introducing bpf_strncmp() helper comes from two aspects: (1) clang doesn't always replace strncmp() automatically In tracing program, sometimes we need to using a home-made strncmp() to check whether or not the file name is expected. (2) the performance of home-made strncmp is not so good As shown in the benchmark in patch #4, the performance of bpf_strncmp() helper is 18% or 33% better than home-made strncmp() under x86-64 or arm64 when the compared string length is 64. When the string length grows to 4095, the performance win will be 179% or 600% under x86-64 or arm64. Any comments are welcome. Regards, Tao Change Log: v2: * rebased on bpf-next * drop patch "selftests/bpf: factor out common helpers for benchmarks" (suggested by Andrii) * remove unnecessary inline functions and add comments for programs which will be rejected by verifier in patch 4 (suggested by Andrii) * rename variables used in will-fail programs to clarify the purposes. v1: https://lore.kernel.org/bpf/20211130142215.1237217-1-houtao1@xxxxxxxxxx * change API to bpf_strncmp(const char *s1, u32 s1_sz, const char *s2) * add benchmark refactor and benchmark between bpf_strncmp() and strncmp() RFC: https://lore.kernel.org/bpf/20211106132822.1396621-1-houtao1@xxxxxxxxxx/ Hou Tao (4): bpf: add bpf_strncmp helper selftests/bpf: fix checkpatch error on empty function parameter selftests/bpf: add benchmark for bpf_strncmp() helper selftests/bpf: add test cases for bpf_strncmp() include/linux/bpf.h | 1 + include/uapi/linux/bpf.h | 11 ++ kernel/bpf/helpers.c | 16 ++ tools/include/uapi/linux/bpf.h | 11 ++ tools/testing/selftests/bpf/Makefile | 4 +- tools/testing/selftests/bpf/bench.c | 8 +- tools/testing/selftests/bpf/bench.h | 9 +- .../selftests/bpf/benchs/bench_count.c | 2 +- .../selftests/bpf/benchs/bench_rename.c | 16 +- .../selftests/bpf/benchs/bench_ringbufs.c | 14 +- .../selftests/bpf/benchs/bench_strncmp.c | 161 +++++++++++++++++ .../selftests/bpf/benchs/bench_trigger.c | 24 +-- .../selftests/bpf/benchs/run_bench_strncmp.sh | 12 ++ .../selftests/bpf/prog_tests/test_strncmp.c | 167 ++++++++++++++++++ .../selftests/bpf/progs/strncmp_bench.c | 50 ++++++ .../selftests/bpf/progs/strncmp_test.c | 54 ++++++ 16 files changed, 526 insertions(+), 34 deletions(-) create mode 100644 tools/testing/selftests/bpf/benchs/bench_strncmp.c create mode 100755 tools/testing/selftests/bpf/benchs/run_bench_strncmp.sh create mode 100644 tools/testing/selftests/bpf/prog_tests/test_strncmp.c create mode 100644 tools/testing/selftests/bpf/progs/strncmp_bench.c create mode 100644 tools/testing/selftests/bpf/progs/strncmp_test.c -- 2.29.2
