runtime: fix trace ticks frequency on windows

Change-Id: I8c7fcc7705070bc9979e39d08a4c9b2870087a08
Reviewed-on: https://go-review.googlesource.com/3500Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

src/runtime/pprof/trace_parser_test.go

@@ -181,6 +181,11 @@ func parseEvents(rawEvents []RawEvent) (events []*Event, err error) {
 			lastTs = int64(raw.args[1])
 		case traceEvFrequency:
 			ticksPerSec = int64(raw.args[0])
+			if ticksPerSec <= 0 {
+				err = fmt.Errorf("traceEvFrequency contains invalid frequency %v at offset 0x%x",
+					ticksPerSec, raw.off)
+				return
+			}
 		case traceEvTimerGoroutine:
 			timerGoid = raw.args[0]
 		case traceEvStack:

src/runtime/pprof/trace_test.go

@@ -19,13 +19,14 @@ import (
 func skipTraceTestsIfNeeded(t *testing.T) {
 	switch runtime.GOOS {
 	case "solaris":
-		t.Skip("skipping: solaris timer can go backwards which is incompatible with tracer (http://golang.org/issue/8976)")
-	case "windows":
-		t.Skip("skipping: windows tests fail with 'failed to parse trace: no traceEvFrequency event'")
-	case "android":
-		t.Skip("skipping: android tests fail with 'failed to parse trace: g 2 is not runnable before traceEvGoWaiting'")
+		t.Skip("skipping: solaris timer can go backwards (http://golang.org/issue/8976)")
 	case "plan9":
-		t.Skip("skipping: plan9 tests fail with 'fatal error: trace: out of memory'")
+		t.Skip("skipping: plan9 tests fail with out of memory (http://golang.org/issue/9712")
+	}
+
+	switch runtime.GOARCH {
+	case "arm":
+		t.Skip("skipping: arm tests fail with 'failed to parse trace' (http://golang.org/issue/9725)")
 	}
 }
 
@@ -233,7 +234,7 @@ eventLoop:
 		for _, f := range ev.stk {
 			if strings.HasSuffix(f.file, "trace_test.go") &&
 				strings.HasSuffix(f.fn, "pprof_test.TestTraceSymbolize") &&
-				f.line == 217 {
+				f.line == 218 {
 				found = true
 				break eventLoop
 			}

src/runtime/trace.go

@@ -208,8 +208,16 @@ func StopTrace() {
 		traceFullQueue(buf)
 	}
 
+	for {
 		trace.ticksEnd = cputicks()
 		trace.timeEnd = nanotime()
+		// Windows time can tick only every 15ms, wait for at least one tick.
+		if trace.timeEnd != trace.timeStart {
+			break
+		}
+		osyield()
+	}
+
 	trace.enabled = false
 	trace.shutdown = true
 	trace.stackTab.dump()