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, 0)
    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, 0)
    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, 0)
    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  }
    76
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