diff options
| -rw-r--r-- | test/syscalls/linux/vdso_clock_gettime.cc | 64 |
1 files changed, 17 insertions, 47 deletions
diff --git a/test/syscalls/linux/vdso_clock_gettime.cc b/test/syscalls/linux/vdso_clock_gettime.cc index ce1899f45..52b67249d 100644 --- a/test/syscalls/linux/vdso_clock_gettime.cc +++ b/test/syscalls/linux/vdso_clock_gettime.cc @@ -38,8 +38,6 @@ std::string PrintClockId(::testing::TestParamInfo<clockid_t> info) { switch (info.param) { case CLOCK_MONOTONIC: return "CLOCK_MONOTONIC"; - case CLOCK_REALTIME: - return "CLOCK_REALTIME"; case CLOCK_BOOTTIME: return "CLOCK_BOOTTIME"; default: @@ -47,59 +45,31 @@ std::string PrintClockId(::testing::TestParamInfo<clockid_t> info) { } } -class CorrectVDSOClockTest : public ::testing::TestWithParam<clockid_t> {}; +class MonotonicVDSOClockTest : public ::testing::TestWithParam<clockid_t> {}; -TEST_P(CorrectVDSOClockTest, IsCorrect) { +TEST_P(MonotonicVDSOClockTest, IsCorrect) { + // Check that when we alternate readings from the clock_gettime syscall and + // the VDSO's implementation, we observe the combined sequence as being + // monotonic. struct timespec tvdso, tsys; absl::Time vdso_time, sys_time; - uint64_t total_calls = 0; - - // It is expected that 82.5% of clock_gettime calls will be less than 100us - // skewed from the system time. - // Unfortunately this is not only influenced by the VDSO clock skew, but also - // by arbitrary scheduling delays and the like. The test is therefore - // regularly disabled. - std::map<absl::Duration, std::tuple<double, uint64_t, uint64_t>> confidence = - { - {absl::Microseconds(100), std::make_tuple(0.825, 0, 0)}, - {absl::Microseconds(250), std::make_tuple(0.94, 0, 0)}, - {absl::Milliseconds(1), std::make_tuple(0.999, 0, 0)}, - }; - - absl::Time start = absl::Now(); - while (absl::Now() < start + absl::Seconds(30)) { - EXPECT_THAT(clock_gettime(GetParam(), &tvdso), SyscallSucceeds()); - EXPECT_THAT(syscall(__NR_clock_gettime, GetParam(), &tsys), - SyscallSucceeds()); - + ASSERT_THAT(syscall(__NR_clock_gettime, GetParam(), &tsys), + SyscallSucceeds()); + sys_time = absl::TimeFromTimespec(tsys); + auto end = absl::Now() + absl::Seconds(10); + while (absl::Now() < end) { + ASSERT_THAT(clock_gettime(GetParam(), &tvdso), SyscallSucceeds()); vdso_time = absl::TimeFromTimespec(tvdso); - - for (auto const& conf : confidence) { - std::get<1>(confidence[conf.first]) += - (sys_time - vdso_time) < conf.first; - } - + EXPECT_LE(sys_time, vdso_time); + ASSERT_THAT(syscall(__NR_clock_gettime, GetParam(), &tsys), + SyscallSucceeds()); sys_time = absl::TimeFromTimespec(tsys); - - for (auto const& conf : confidence) { - std::get<2>(confidence[conf.first]) += - (vdso_time - sys_time) < conf.first; - } - - ++total_calls; - } - - for (auto const& conf : confidence) { - EXPECT_GE(std::get<1>(conf.second) / static_cast<double>(total_calls), - std::get<0>(conf.second)); - EXPECT_GE(std::get<2>(conf.second) / static_cast<double>(total_calls), - std::get<0>(conf.second)); + EXPECT_LE(vdso_time, sys_time); } } -INSTANTIATE_TEST_SUITE_P(ClockGettime, CorrectVDSOClockTest, - ::testing::Values(CLOCK_MONOTONIC, CLOCK_REALTIME, - CLOCK_BOOTTIME), +INSTANTIATE_TEST_SUITE_P(ClockGettime, MonotonicVDSOClockTest, + ::testing::Values(CLOCK_MONOTONIC, CLOCK_BOOTTIME), PrintClockId); } // namespace |