mirror of
https://github.com/netbirdio/gvisor.git
synced 2026-05-22 17:12:49 -07:00
Ghanan Gowripalan
15fdd74e5c
...since `select` only supports FD values up to 1024 and creating 1024 event FDs will result in FD values that are greater than 1024 because of the initial set of FDs that exist for most programs (stdin, stdout, stderr). https://www.man7.org/linux/man-pages/man2/select.2.html PiperOrigin-RevId: 573916775
105 lines
3.0 KiB
C++
105 lines
3.0 KiB
C++
// Copyright 2023 The gVisor Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <sys/select.h>
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#include <cstdint>
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#include <utility>
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#include <vector>
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#include "gmock/gmock.h"
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#include "gtest/gtest.h"
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#include "benchmark/benchmark.h"
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#include "test/util/eventfd_util.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/posix_error.h"
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#include "test/util/test_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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// Populates |event_fds| with new event FDs and |read_fds| with each new event
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// FD.
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void Setup(int count, std::vector<FileDescriptor>& event_fds, fd_set& read_fds,
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int& max_fd) {
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max_fd = -1;
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FD_ZERO(&read_fds);
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for (int i = 0; i < count; ++i) {
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FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(NewEventFD());
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if (fd.get() > max_fd) {
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max_fd = fd.get();
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}
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FD_SET(fd.get(), &read_fds);
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event_fds.push_back(std::move(fd));
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}
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ASSERT_LT(max_fd, FD_SETSIZE);
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}
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// Benchmarks a call to select(2) when no FD is "ready" with varying timeout
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// values.
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void BM_SelectTimeout(benchmark::State& state) {
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constexpr int kFDsPerSelect = 3;
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std::vector<FileDescriptor> event_fds;
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fd_set read_fds;
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int max_fd;
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ASSERT_NO_FATAL_FAILURE(Setup(kFDsPerSelect, event_fds, read_fds, max_fd));
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const int timeout_ms = state.range(0);
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timeval timeout = {
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.tv_sec = 0,
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.tv_usec = timeout_ms * 1000,
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};
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for (auto _ : state) {
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EXPECT_EQ(select(max_fd + 1, &read_fds, /*writefds=*/nullptr,
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/*exceptfds=*/nullptr, &timeout),
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0);
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}
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}
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BENCHMARK(BM_SelectTimeout)->Range(/*start=*/0, /*limit=*/8);
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// Benchmarks a call to select(2) with a zero timeout and varying number of
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// "ready" FDs.
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void BM_SelectAllEvents(benchmark::State& state) {
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const int fds_per_select = state.range(0);
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std::vector<FileDescriptor> event_fds;
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fd_set read_fds;
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int max_fd;
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ASSERT_NO_FATAL_FAILURE(Setup(fds_per_select, event_fds, read_fds, max_fd));
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constexpr uint64_t kEventVal = 5;
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for (const auto& eventfd : event_fds) {
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ASSERT_THAT(WriteFd(eventfd.get(), &kEventVal, sizeof(kEventVal)),
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SyscallSucceedsWithValue(sizeof(kEventVal)));
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}
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timeval timeout = {};
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for (auto _ : state) {
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EXPECT_EQ(select(max_fd + 1, &read_fds, /*writefds=*/nullptr,
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/*exceptfds=*/nullptr, &timeout),
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fds_per_select);
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}
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}
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BENCHMARK(BM_SelectAllEvents)->Range(/*start=*/2, /*limit=*/512);
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} // namespace
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} // namespace testing
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} // namespace gvisor
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