libgo/go/runtime/norace_test.go

   1 // Copyright 2013 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // The file contains tests that cannot run under race detector for some reason.
   6 // +build !race
   7
   8 package runtime_test
   9
  10 import (
  11         "runtime"
  12         "testing"
  13 )
  14
  15 // Syscall tests split stack between Entersyscall and Exitsyscall under race detector.
  16 func BenchmarkSyscall(b *testing.B) {
  17         benchmarkSyscall(b, 0, 1)
  18 }
  19
  20 func BenchmarkSyscallWork(b *testing.B) {
  21         benchmarkSyscall(b, 100, 1)
  22 }
  23
  24 func BenchmarkSyscallExcess(b *testing.B) {
  25         benchmarkSyscall(b, 0, 4)
  26 }
  27
  28 func BenchmarkSyscallExcessWork(b *testing.B) {
  29         benchmarkSyscall(b, 100, 4)
  30 }
  31
  32 func benchmarkSyscall(b *testing.B, work, excess int) {
  33         b.SetParallelism(excess)
  34         b.RunParallel(func(pb *testing.PB) {
  35                 foo := 42
  36                 for pb.Next() {
  37                         runtime.Entersyscall(0)
  38                         for i := 0; i < work; i++ {
  39                                 foo *= 2
  40                                 foo /= 2
  41                         }
  42                         runtime.Exitsyscall(0)
  43                 }
  44                 _ = foo
  45         })
  46 }