github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/test/perf/linux/clock_getres_benchmark.cc (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  #include <time.h>
    16  
    17  #include "gtest/gtest.h"
    18  #include "benchmark/benchmark.h"
    19  
    20  namespace gvisor {
    21  namespace testing {
    22  
    23  namespace {
    24  
    25  // clock_getres(1) is very nearly a no-op syscall, but it does require copying
    26  // out to a userspace struct. It thus provides a nice small copy-out benchmark.
    27  void BM_ClockGetRes(benchmark::State& state) {
    28    struct timespec ts;
    29    for (auto _ : state) {
    30      clock_getres(CLOCK_MONOTONIC, &ts);
    31    }
    32  }
    33  
    34  BENCHMARK(BM_ClockGetRes);
    35  
    36  }  // namespace
    37  
    38  }  // namespace testing
    39  }  // namespace gvisor