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Deflake vdso_clock_gettime test.

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PiperOrigin-RevId: 332281930
This commit is contained in:
Jamie Liu
2020-09-17 11:59:55 -07:00
committed by gVisor bot
parent 51a2fe8eb4
commit f0b1bd434e
1 changed files with 17 additions and 47 deletions
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test/syscalls/linux/vdso_clock_gettime.cc
+17 -47
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@@ -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