libgo/go/sync/runtime_sema_test.go

   1 // Copyright 2009 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 package sync_test
   6
   7 import (
   8         "runtime"
   9         . "sync"
  10         "testing"
  11 )
  12
  13 func BenchmarkSemaUncontended(b *testing.B) {
  14         type PaddedSem struct {
  15                 sem uint32
  16                 pad [32]uint32
  17         }
  18         b.RunParallel(func(pb *testing.PB) {
  19                 sem := new(PaddedSem)
  20                 for pb.Next() {
  21                         Runtime_Semrelease(&sem.sem, false)
  22                         Runtime_Semacquire(&sem.sem)
  23                 }
  24         })
  25 }
  26
  27 func benchmarkSema(b *testing.B, block, work bool) {
  28         if b.N == 0 {
  29                 return
  30         }
  31         sem := uint32(0)
  32         if block {
  33                 done := make(chan bool)
  34                 go func() {
  35                         for p := 0; p < runtime.GOMAXPROCS(0)/2; p++ {
  36                                 Runtime_Semacquire(&sem)
  37                         }
  38                         done <- true
  39                 }()
  40                 defer func() {
  41                         <-done
  42                 }()
  43         }
  44         b.RunParallel(func(pb *testing.PB) {
  45                 foo := 0
  46                 for pb.Next() {
  47                         Runtime_Semrelease(&sem, false)
  48                         if work {
  49                                 for i := 0; i < 100; i++ {
  50                                         foo *= 2
  51                                         foo /= 2
  52                                 }
  53                         }
  54                         Runtime_Semacquire(&sem)
  55                 }
  56                 _ = foo
  57                 Runtime_Semrelease(&sem, false)
  58         })
  59 }
  60
  61 func BenchmarkSemaSyntNonblock(b *testing.B) {
  62         benchmarkSema(b, false, false)
  63 }
  64
  65 func BenchmarkSemaSyntBlock(b *testing.B) {
  66         benchmarkSema(b, true, false)
  67 }
  68
  69 func BenchmarkSemaWorkNonblock(b *testing.B) {
  70         benchmarkSema(b, false, true)
  71 }
  72
  73 func BenchmarkSemaWorkBlock(b *testing.B) {
  74         benchmarkSema(b, true, true)
  75 }