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 can not run under race detector for some reason.
   6 // +build !race
   7
   8 package runtime_test
   9
  10 import (
  11         "runtime"
  12         "sync/atomic"
  13         "testing"
  14 )
  15
  16 // Syscall tests split stack between Entersyscall and Exitsyscall under race detector.
  17 func BenchmarkSyscall(b *testing.B) {
  18         benchmarkSyscall(b, 0, 1)
  19 }
  20
  21 func BenchmarkSyscallWork(b *testing.B) {
  22         benchmarkSyscall(b, 100, 1)
  23 }
  24
  25 func BenchmarkSyscallExcess(b *testing.B) {
  26         benchmarkSyscall(b, 0, 4)
  27 }
  28
  29 func BenchmarkSyscallExcessWork(b *testing.B) {
  30         benchmarkSyscall(b, 100, 4)
  31 }
  32
  33 func benchmarkSyscall(b *testing.B, work, excess int) {
  34         const CallsPerSched = 1000
  35         procs := runtime.GOMAXPROCS(-1) * excess
  36         N := int32(b.N / CallsPerSched)
  37         c := make(chan bool, procs)
  38         for p := 0; p < procs; p++ {
  39                 go func() {
  40                         foo := 42
  41                         for atomic.AddInt32(&N, -1) >= 0 {
  42                                 runtime.Gosched()
  43                                 for g := 0; g < CallsPerSched; g++ {
  44                                         runtime.Entersyscall()
  45                                         for i := 0; i < work; i++ {
  46                                                 foo *= 2
  47                                                 foo /= 2
  48                                         }
  49                                         runtime.Exitsyscall()
  50                                 }
  51                         }
  52                         c <- foo == 42
  53                 }()
  54         }
  55         for p := 0; p < procs; p++ {
  56                 <-c
  57         }
  58 }