Re: [PATCHv5 bpf-next 25/28] selftests/bpf: Add uprobe_multi usdt bench test

Alexei Starovoitov
2023-08-01T17:51:50Z

On Sun, Jul 30, 2023 at 6:46 AM Jiri Olsa <jolsa@kernel.org> wrote:
>
> Adding test that attaches 50k usdt probes in usdt_multi binary.
>
> After the attach is done we run the binary and make sure we get
> proper amount of hits.
>
> With current uprobes:
>
> # perf stat --null ./test_progs -n 254/6
> #254/6 uprobe_multi_test/bench_usdt:OK
> #254 uprobe_multi_test:OK
> Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
>
> Performance counter stats for './test_progs -n 254/6':
>
> 1353.659680562 seconds time elapsed
>
> With uprobe_multi link:
>
> # perf stat --null ./test_progs -n 254/6
> #254/6 uprobe_multi_test/bench_usdt:OK
> #254 uprobe_multi_test:OK
> Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED
>
> Performance counter stats for './test_progs -n 254/6':
>
> 0.322046364 seconds time elapsed
>
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
> .../bpf/prog_tests/uprobe_multi_test.c | 39 +++++++++++++++++++
> .../selftests/bpf/progs/uprobe_multi_usdt.c | 16 ++++++++
> 2 files changed, 55 insertions(+)
> create mode 100644 tools/testing/selftests/bpf/progs/uprobe_multi_usdt.c
>
> diff --git a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> index 56c2062af1c9..19a66431a61f 100644
> --- a/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> +++ b/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c
> @@ -4,6 +4,7 @@
> #include <test_progs.h>
> #include "uprobe_multi.skel.h"
> #include "uprobe_multi_bench.skel.h"
> +#include "uprobe_multi_usdt.skel.h"
> #include "bpf/libbpf_internal.h"
> #include "testing_helpers.h"
>
> @@ -234,6 +235,42 @@ static void test_bench_attach_uprobe(void)
> printf("%s: detached in %7.3lfs\n", __func__, detach_delta);
> }
>
> +static void test_bench_attach_usdt(void)
> +{
> + struct uprobe_multi_usdt *skel = NULL;
> + long attach_start_ns, attach_end_ns;
> + long detach_start_ns, detach_end_ns;
> + double attach_delta, detach_delta;
> +
> + skel = uprobe_multi_usdt__open_and_load();
> + if (!ASSERT_OK_PTR(skel, "uprobe_multi__open"))
> + goto cleanup;
> +
> + attach_start_ns = get_time_ns();
> +
> + skel->links.usdt0 = bpf_program__attach_usdt(skel->progs.usdt0, -1, "./uprobe_multi",
> + "test", "usdt", NULL);
> + if (!ASSERT_OK_PTR(skel->links.usdt0, "bpf_program__attach_usdt"))
> + goto cleanup;
> +
> + attach_end_ns = get_time_ns();
> +
> + system("./uprobe_multi usdt");
> +
> + ASSERT_EQ(skel->bss->count, 50000, "usdt_count");
> +
> +cleanup:
> + detach_start_ns = get_time_ns();
> + uprobe_multi_usdt__destroy(skel);
> + detach_end_ns = get_time_ns();
> +
> + attach_delta = (attach_end_ns - attach_start_ns) / 1000000000.0;
> + detach_delta = (detach_end_ns - detach_start_ns) / 1000000000.0;
> +
> + printf("%s: attached in %7.3lfs\n", __func__, attach_delta);
> + printf("%s: detached in %7.3lfs\n", __func__, detach_delta);
> +}

It fails CI.
/tmp/work/bpf/bpf/tools/testing/selftests/bpf/prog_tests/uprobe_multi_test.c:338:6:
error: variable 'attach_start_ns' is used uninitialized whenever 'if'
condition is true [-Werror,-Wsometimes-uninitialized]
if (!ASSERT_OK_PTR(skel, "uprobe_multi__open"))