runtime: use GetQueuedCompletionStatusEx on windows if available
GetQueuedCompletionStatusEx allows to dequeue a batch of completion
notifications, which is more efficient than dequeueing one by one.
benchmark old ns/op new ns/op delta
BenchmarkClientServerParallel4 100605 90945 -9.60%
BenchmarkClientServerParallel4-2 90225 74504 -17.42%
R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/12436044
diff --git a/src/pkg/runtime/runtime.h b/src/pkg/runtime/runtime.h
index 55ae16e..2529a0f 100644
--- a/src/pkg/runtime/runtime.h
+++ b/src/pkg/runtime/runtime.h
@@ -853,6 +853,7 @@
int32 runtime·netpollopen(uintptr, PollDesc*);
int32 runtime·netpollclose(uintptr);
void runtime·netpollready(G**, PollDesc*, int32);
+uintptr runtime·netpollfd(PollDesc*);
void runtime·crash(void);
void runtime·parsedebugvars(void);
void _rt0_go(void);
