A method of operating a graphics processing unit includes determining, based on input data, whether to perform a tiling operation before or after a tessellation operation and performing the tiling operation according to the determination result. Performing the tiling operation after the tessellation operation if the input data is not a patch, and if a geometry of the patch is at the out-side of a convex hull defined by control points of the patch. Performing the tiling operation after the tessellation operation if a geometry of a tessellated primitive corresponding to the patch changes according to a shading operation.