diff --git a/pcdet/ops/pointnet2/pointnet2_batch/src/cuda_utils.h b/pcdet/ops/pointnet2/pointnet2_batch/src/cuda_utils.h
new file mode 100644
index 0000000..7fe2796
--- /dev/null
+++ b/pcdet/ops/pointnet2/pointnet2_batch/src/cuda_utils.h
@@ -0,0 +1,15 @@
+#ifndef _CUDA_UTILS_H
+#define _CUDA_UTILS_H
+
+#include <cmath>
+
+#define TOTAL_THREADS 1024
+#define THREADS_PER_BLOCK 256
+#define DIVUP(m,n) ((m) / (n) + ((m) % (n) > 0))
+
+inline int opt_n_threads(int work_size) {
+    const int pow_2 = std::log(static_cast<double>(work_size)) / std::log(2.0);
+
+    return max(min(1 << pow_2, TOTAL_THREADS), 1);
+}
+#endif