From 68cf8cc9a244041f859dc484abe551b8e018ad05 Mon Sep 17 00:00:00 2001
From: Andrei Vagin <avagin@gmail.com>
Date: Sat, 24 Jul 2021 17:09:33 -0700
Subject: Don't create an extra fd bitmap to allocate a new fd.

---
 test/perf/BUILD                  |  7 +++++
 test/perf/linux/BUILD            | 16 +++++++++++
 test/perf/linux/dup_benchmark.cc | 57 ++++++++++++++++++++++++++++++++++++++++
 test/syscalls/linux/BUILD        |  1 +
 test/syscalls/linux/dup.cc       | 38 +++++++++++++++++++++++++++
 5 files changed, 119 insertions(+)
 create mode 100644 test/perf/linux/dup_benchmark.cc

(limited to 'test')

diff --git a/test/perf/BUILD b/test/perf/BUILD
index 75b5003e2..08e04d8ad 100644
--- a/test/perf/BUILD
+++ b/test/perf/BUILD
@@ -69,6 +69,13 @@ syscall_test(
     test = "//test/perf/linux:open_benchmark",
 )
 
+syscall_test(
+    size = "large",
+    add_overlay = True,
+    debug = False,
+    test = "//test/perf/linux:dup_benchmark",
+)
+
 syscall_test(
     debug = False,
     test = "//test/perf/linux:pipe_benchmark",
diff --git a/test/perf/linux/BUILD b/test/perf/linux/BUILD
index dd1d2438c..4511611ad 100644
--- a/test/perf/linux/BUILD
+++ b/test/perf/linux/BUILD
@@ -108,6 +108,22 @@ cc_binary(
     ],
 )
 
+cc_binary(
+    name = "dup_benchmark",
+    testonly = 1,
+    srcs = [
+        "dup_benchmark.cc",
+    ],
+    deps = [
+        gbenchmark,
+        gtest,
+        "//test/util:fs_util",
+        "//test/util:logging",
+        "//test/util:temp_path",
+        "//test/util:test_main",
+    ],
+)
+
 cc_binary(
     name = "read_benchmark",
     testonly = 1,
diff --git a/test/perf/linux/dup_benchmark.cc b/test/perf/linux/dup_benchmark.cc
new file mode 100644
index 000000000..fcf14368b
--- /dev/null
+++ b/test/perf/linux/dup_benchmark.cc
@@ -0,0 +1,57 @@
+// Copyright 2020 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 <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "gtest/gtest.h"
+#include "benchmark/benchmark.h"
+#include "test/util/fs_util.h"
+#include "test/util/logging.h"
+#include "test/util/temp_path.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+void BM_Dup(benchmark::State& state) {
+  const int size = state.range(0);
+
+  for (auto _ : state) {
+    std::vector<int> v;
+    for (int i = 0; i < size; i++) {
+      int fd = dup(2);
+      TEST_CHECK(fd != -1);
+      v.push_back(fd);
+    }
+    for (int i = 0; i < size; i++) {
+      int fd = v[i];
+      close(fd);
+    }
+  }
+  state.SetItemsProcessed(state.iterations() * size);
+}
+
+BENCHMARK(BM_Dup)->Range(1, 1 << 15)->UseRealTime();
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor
diff --git a/test/syscalls/linux/BUILD b/test/syscalls/linux/BUILD
index 2bf685524..1bbcd8abb 100644
--- a/test/syscalls/linux/BUILD
+++ b/test/syscalls/linux/BUILD
@@ -583,6 +583,7 @@ cc_binary(
     deps = [
         "//test/util:eventfd_util",
         "//test/util:file_descriptor",
+        "@com_google_absl//absl/memory",
         gtest,
         "//test/util:fs_util",
         "//test/util:posix_error",
diff --git a/test/syscalls/linux/dup.cc b/test/syscalls/linux/dup.cc
index ba4e13fb9..fca0880a6 100644
--- a/test/syscalls/linux/dup.cc
+++ b/test/syscalls/linux/dup.cc
@@ -13,9 +13,11 @@
 // limitations under the License.
 
 #include <fcntl.h>
+#include <sys/resource.h>
 #include <unistd.h>
 
 #include "gtest/gtest.h"
+#include "absl/memory/memory.h"
 #include "test/util/eventfd_util.h"
 #include "test/util/file_descriptor.h"
 #include "test/util/fs_util.h"
@@ -98,6 +100,42 @@ TEST(DupTest, Dup2) {
   ASSERT_NO_ERRNO(CheckSameFile(fd, nfd2));
 }
 
+TEST(DupTest, Rlimit) {
+  constexpr int kFDLimit = 101;
+  auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
+  FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));
+
+  struct rlimit rl = {};
+  EXPECT_THAT(getrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
+
+  // Lower the rlimit first, as it may be equal to /proc/sys/fs/nr_open, in
+  // which case even users with CAP_SYS_RESOURCE can't raise it.
+  rl.rlim_cur = kFDLimit * 2;
+  ASSERT_THAT(setrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
+
+  FileDescriptor aboveLimitFD =
+      ASSERT_NO_ERRNO_AND_VALUE(Dup2(fd, kFDLimit * 2 - 1));
+
+  rl.rlim_cur = kFDLimit;
+  ASSERT_THAT(setrlimit(RLIMIT_NOFILE, &rl), SyscallSucceeds());
+  ASSERT_THAT(dup3(fd.get(), kFDLimit, 0), SyscallFails());
+
+  std::vector<std::unique_ptr<FileDescriptor>> fds;
+  int prev = fd.get();
+  for (int i = 0; i < kFDLimit; i++) {
+    int d = dup(fd.get());
+    if (d == -1) {
+      break;
+    }
+    std::unique_ptr<FileDescriptor> f = absl::make_unique<FileDescriptor>(d);
+    EXPECT_LT(d, kFDLimit);
+    EXPECT_GT(d, prev);
+    prev = d;
+    fds.push_back(std::move(f));
+  }
+  EXPECT_EQ(fds.size(), kFDLimit - fd.get() - 1);
+}
+
 TEST(DupTest, Dup2SameFD) {
   auto f = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
   FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(Open(f.path(), O_RDONLY));
-- 
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