message: Improve performance of small scalar reductions on GPU
diff: @@ -500,7 +500,7 @@ void LaunchScalarReduction(OpKernelContext* ctx, OUT_T out, IN_T in,
  BlockReduceKernel<IN_T, OUT_T, num_threads>
  <<<num_blocks, num_threads, 0, cu_stream>>>(in, out, in_size, op, init);
  return;
  - } else if (in_size <= 1 << 19) {
  + } else if (in_size <= 1 << 18) {
  const int num_threads = 256;
  const int num_blocks = std::min(32, Eigen::divup(in_size, num_threads));
  // it seems like tailoring this to the GPU
  