On Mon, Aug 16, 2021 at 10:54 AM Yucong Sun <fallentree@xxxxxx> wrote:
>
> Using a fixed delay of 1ms is proven flaky in slow CPU environment, eg. github
> action CI system. This patch adds exponential backoff with a cap of 50ms, to
> reduce the flakyness of the test.
Do we have data showing how flaky the test is before and after this change?
>
> Signed-off-by: Yucong Sun <fallentree@xxxxxx>
> ---
> tools/testing/selftests/bpf/test_maps.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/tools/testing/selftests/bpf/test_maps.c b/tools/testing/selftests/bpf/test_maps.c
> index 14cea869235b..ed92d56c19cf 100644
> --- a/tools/testing/selftests/bpf/test_maps.c
> +++ b/tools/testing/selftests/bpf/test_maps.c
> @@ -1400,11 +1400,16 @@ static void test_map_stress(void)
> static int map_update_retriable(int map_fd, const void *key, const void *value,
> int flags, int attempts)
> {
> + int delay = 1;
> +
> while (bpf_map_update_elem(map_fd, key, value, flags)) {
> if (!attempts || (errno != EAGAIN && errno != EBUSY))
> return -errno;
>
> - usleep(1);
> + if (delay < 50)
> + delay *= 2;
> +
> + usleep(delay);
It is a little weird that the delay times in microseconds are 2, 4, 8,
16, 32, 64, 64, ...
Maybe just use rand()?
Thanks,
Song
> attempts--;
> }
>
> --
> 2.30.2
>
