Thank !!
i added this command line. My code:
import Net;

net = Net();
torch.cuda.synchronize()

@profile
def train(epoch):
    net.train();
for batch_idx,(data1, label) in enumerate(trainloader,0):
        data  = Variable(data1).cuda();
        label = Variable(label).cuda();
        optimizer.zero_grad();
        output_2 = net(data);
        output_1 = net(data);
        output_3 = net(data);

But the result is the same compare to not add torch.cuda.synchronize()