On Wed, Oct 6, 2021 at 11:56 AM Yucong Sun <fallentree@xxxxxx> wrote:
>
> From: Yucong Sun <sunyucong@xxxxxxxxx>
>
> This patch moved a helper function to test_progs and make all tests
> setting sampling frequency use it to read current perf_max_sample_freq,
> this will avoid triggering EINVAL error.
>
> Signed-off-by: Yucong Sun <sunyucong@xxxxxxxxx>
> ---
> .../selftests/bpf/prog_tests/bpf_cookie.c | 2 +-
> .../selftests/bpf/prog_tests/perf_branches.c | 4 ++--
> .../selftests/bpf/prog_tests/perf_link.c | 2 +-
> .../bpf/prog_tests/stacktrace_build_id_nmi.c | 19 ++-----------------
> tools/testing/selftests/bpf/test_progs.c | 15 +++++++++++++++
> tools/testing/selftests/bpf/test_progs.h | 1 +
> 6 files changed, 22 insertions(+), 21 deletions(-)
>
We have trace_helper.c, seems like it would be better to have it
there? I haven't applied this patch yet.
[...]
> @@ -48,6 +31,8 @@ void test_stacktrace_build_id_nmi(void)
> if (CHECK(err, "skel_load", "skeleton load failed: %d\n", err))
> goto cleanup;
>
> + attr.sample_freq = read_perf_max_sample_freq();
> +
> pmu_fd = syscall(__NR_perf_event_open, &attr, -1 /* pid */,
> 0 /* cpu 0 */, -1 /* group id */,
> 0 /* flags */);
> diff --git a/tools/testing/selftests/bpf/test_progs.c b/tools/testing/selftests/bpf/test_progs.c
> index 2ac922f8aa2c..66825313414b 100644
> --- a/tools/testing/selftests/bpf/test_progs.c
> +++ b/tools/testing/selftests/bpf/test_progs.c
> @@ -1500,3 +1500,18 @@ int main(int argc, char **argv)
>
> return env.fail_cnt ? EXIT_FAILURE : EXIT_SUCCESS;
> }
> +
> +__u64 read_perf_max_sample_freq(void)
> +{
> + __u64 sample_freq = 1000; /* fallback to 1000 on error */
previous default was 5000, message below still claims 5000, what's the
reason for changing it?
> + FILE *f;
> + __u32 duration = 0;
> +
> + f = fopen("/proc/sys/kernel/perf_event_max_sample_rate", "r");
> + if (f == NULL)
> + return sample_freq;
> + CHECK(fscanf(f, "%llu", &sample_freq) != 1, "Get max sample rate",
> + "return default value: 5000,err %d\n", -errno);
> + fclose(f);
> + return sample_freq;
> +}
> diff --git a/tools/testing/selftests/bpf/test_progs.h b/tools/testing/selftests/bpf/test_progs.h
> index b239dc9fcef0..d5ca0d36cc96 100644
> --- a/tools/testing/selftests/bpf/test_progs.h
> +++ b/tools/testing/selftests/bpf/test_progs.h
> @@ -327,6 +327,7 @@ int extract_build_id(char *build_id, size_t size);
> int kern_sync_rcu(void);
> int trigger_module_test_read(int read_sz);
> int trigger_module_test_write(int write_sz);
> +__u64 read_perf_max_sample_freq(void);
>
> #ifdef __x86_64__
> #define SYS_NANOSLEEP_KPROBE_NAME "__x64_sys_nanosleep"
> --
> 2.30.2
>
