1 files changed, 36 insertions, 6 deletions
diff --git a/misc/cgo/test/issue1560.go b/misc/cgo/test/issue1560.go
index 3faa966e7..147ce94b5 100644
--- a/misc/cgo/test/issue1560.go
+++ b/misc/cgo/test/issue1560.go
@@ -15,6 +15,7 @@ void twoSleep(int);
 import "C"
 
 import (
+	"runtime"
 	"testing"
 	"time"
 )
@@ -27,19 +28,48 @@ func parallelSleep(n int) {
 }
 
 //export BackgroundSleep
-func BackgroundSleep(n int) {
+func BackgroundSleep(n int32) {
 	go func() {
 		C.sleep(C.uint(n))
 		sleepDone <- true
 	}()
 }
 
+// wasteCPU starts a background goroutine to waste CPU
+// to cause the power management to raise the CPU frequency.
+// On ARM this has the side effect of making sleep more accurate.
+func wasteCPU() chan struct{} {
+	done := make(chan struct{})
+	go func() {
+		for {
+			select {
+			case <-done:
+				return
+			default:
+			}
+		}
+	}()
+	// pause for a short amount of time to allow the
+	// power management to recognise load has risen.
+	<-time.After(300 * time.Millisecond)
+	return done
+}
+
 func testParallelSleep(t *testing.T) {
+	if runtime.GOARCH == "arm" {
+		// on ARM, the 1.3s deadline is frequently missed,
+		// and burning cpu seems to help
+		defer runtime.GOMAXPROCS(runtime.GOMAXPROCS(2))
+		defer close(wasteCPU())
+	}
+
+	sleepSec := 1
 	start := time.Now()
-	parallelSleep(1)
-	dt := time.Now().Sub(start)
-	// bug used to run sleeps in serial, producing a 2-second delay.
-	if dt >= 1300*time.Millisecond {
-		t.Fatalf("parallel 1-second sleeps slept for %f seconds", dt.Seconds())
+	parallelSleep(sleepSec)
+	dt := time.Since(start)
+	t.Logf("sleep(%d) slept for %v", sleepSec, dt)
+	// bug used to run sleeps in serial, producing a 2*sleepSec-second delay.
+	if dt >= time.Duration(sleepSec)*1300*time.Millisecond {
+		t.Fatalf("parallel %d-second sleeps slept for %f seconds", sleepSec, dt.Seconds())
 	}
 }