1 files changed, 105 insertions, 0 deletions
diff --git a/libgo/go/sync/waitgroup_test.go b/libgo/go/sync/waitgroup_test.go
index fe35732e7a6..34430fc2158 100644
--- a/libgo/go/sync/waitgroup_test.go
+++ b/libgo/go/sync/waitgroup_test.go
@@ -5,7 +5,9 @@
 package sync_test
 
 import (
+	"runtime"
 	. "sync"
+	"sync/atomic"
 	"testing"
 )
 
@@ -58,3 +60,106 @@ func TestWaitGroupMisuse(t *testing.T) {
 	wg.Done()
 	t.Fatal("Should panic")
 }
+
+func BenchmarkWaitGroupUncontended(b *testing.B) {
+	type PaddedWaitGroup struct {
+		WaitGroup
+		pad [128]uint8
+	}
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	for p := 0; p < procs; p++ {
+		go func() {
+			var wg PaddedWaitGroup
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					wg.Add(1)
+					wg.Done()
+					wg.Wait()
+				}
+			}
+			c <- true
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}
+
+func benchmarkWaitGroupAddDone(b *testing.B, localWork int) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	var wg WaitGroup
+	for p := 0; p < procs; p++ {
+		go func() {
+			foo := 0
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					wg.Add(1)
+					for i := 0; i < localWork; i++ {
+						foo *= 2
+						foo /= 2
+					}
+					wg.Done()
+				}
+			}
+			c <- foo == 42
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}
+
+func BenchmarkWaitGroupAddDone(b *testing.B) {
+	benchmarkWaitGroupAddDone(b, 0)
+}
+
+func BenchmarkWaitGroupAddDoneWork(b *testing.B) {
+	benchmarkWaitGroupAddDone(b, 100)
+}
+
+func benchmarkWaitGroupWait(b *testing.B, localWork int) {
+	const CallsPerSched = 1000
+	procs := runtime.GOMAXPROCS(-1)
+	N := int32(b.N / CallsPerSched)
+	c := make(chan bool, procs)
+	var wg WaitGroup
+	wg.Add(procs)
+	for p := 0; p < procs; p++ {
+		go wg.Done()
+	}
+	for p := 0; p < procs; p++ {
+		go func() {
+			foo := 0
+			for atomic.AddInt32(&N, -1) >= 0 {
+				runtime.Gosched()
+				for g := 0; g < CallsPerSched; g++ {
+					wg.Wait()
+					for i := 0; i < localWork; i++ {
+						foo *= 2
+						foo /= 2
+					}
+				}
+			}
+			c <- foo == 42
+		}()
+	}
+	for p := 0; p < procs; p++ {
+		<-c
+	}
+}
+
+func BenchmarkWaitGroupWait(b *testing.B) {
+	benchmarkWaitGroupWait(b, 0)
+}
+
+func BenchmarkWaitGroupWaitWork(b *testing.B) {
+	benchmarkWaitGroupWait(b, 100)
+}