github.com/sean-/go@v0.0.0-20151219100004-97f854cd7bb6/src/sync/runtime_sema_test.go (about)

     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)
    22  			Runtime_Semacquire(&sem.sem)
    23  		}
    24  	})
    25  }
    26  
    27  func benchmarkSema(b *testing.B, block, work bool) {
    28  	sem := uint32(0)
    29  	if block {
    30  		done := make(chan bool)
    31  		go func() {
    32  			for p := 0; p < runtime.GOMAXPROCS(0)/2; p++ {
    33  				Runtime_Semacquire(&sem)
    34  			}
    35  			done <- true
    36  		}()
    37  		defer func() {
    38  			<-done
    39  		}()
    40  	}
    41  	b.RunParallel(func(pb *testing.PB) {
    42  		foo := 0
    43  		for pb.Next() {
    44  			Runtime_Semrelease(&sem)
    45  			if work {
    46  				for i := 0; i < 100; i++ {
    47  					foo *= 2
    48  					foo /= 2
    49  				}
    50  			}
    51  			Runtime_Semacquire(&sem)
    52  		}
    53  		_ = foo
    54  		Runtime_Semrelease(&sem)
    55  	})
    56  }
    57  
    58  func BenchmarkSemaSyntNonblock(b *testing.B) {
    59  	benchmarkSema(b, false, false)
    60  }
    61  
    62  func BenchmarkSemaSyntBlock(b *testing.B) {
    63  	benchmarkSema(b, true, false)
    64  }
    65  
    66  func BenchmarkSemaWorkNonblock(b *testing.B) {
    67  	benchmarkSema(b, false, true)
    68  }
    69  
    70  func BenchmarkSemaWorkBlock(b *testing.B) {
    71  	benchmarkSema(b, true, true)
    72  }