setstream(1);
NullKernel; streamsync;
loop(100000); NullKernel; streamsync; endloop(1);

loop(100000); H2D;  streamsync; NullKernel; streamsync; endloop(1);

loop(100000); H2D;  streamsync; NullKernel; streamsync; D2H;  streamsync; endloop(1);