ATI Radeon HD 4800

Ultra Threaded Dispatch Processor 3.0?

The task dispatcher is a key component of every modern GPU. Its job is to distribute the overall load uniformly among the available GPU resources in order to achieve maximum performance.

The task dispatcher first appeared in the ATI Radeon X1000 series where it could control 512 code branches with 16 pixels in each. The second version of the dispatch processor was introduced in the Radeon HD 2000: it could process more code branches in a more efficient manner as the minimum size of a branch was reduced from 16 to 5 pixels.

There is no accurate information about this aspect of the RV770 but it is clear that the number of arbiters and sequencers has been increased along with the number of SIMD arrays. Besides, each SIMD array can now use data from another one which required certain modifications of the dispatcher’s algorithm. Additionally, the Radeon 4800 architecture features a number of GPGPU optimizations which may also mean changes in the dispatcher’s operation.