// Copyright 2018 The gVisor Authors. // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. #include <stdint.h> #include <sys/time.h> #include <syscall.h> #include <time.h> #include <unistd.h> #include <map> #include <string> #include <utility> #include "gmock/gmock.h" #include "gtest/gtest.h" #include "absl/strings/numbers.h" #include "absl/time/clock.h" #include "absl/time/time.h" #include "test/util/test_util.h" namespace gvisor { namespace testing { namespace { 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: return absl::StrCat(info.param); } } class CorrectVDSOClockTest : public ::testing::TestWithParam<clockid_t> {}; TEST_P(CorrectVDSOClockTest, IsCorrect) { 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()); vdso_time = absl::TimeFromTimespec(tvdso); for (auto const& conf : confidence) { std::get<1>(confidence[conf.first]) += (sys_time - vdso_time) < conf.first; } 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)); } } INSTANTIATE_TEST_SUITE_P(ClockGettime, CorrectVDSOClockTest, ::testing::Values(CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME), PrintClockId); } // namespace } // namespace testing } // namespace gvisor