1. A method for computing credit values for groups of threads, comprising: issuing a first instruction for execution by a first group of threads in a streaming multiprocessor during an issue cycle; determining a warp identifier associated with the first group of threads; updating a first warp credit for the first group of threads that is associated with the warp identifier; and updating a second warp credit for a second group of threads that is associated with a different warp identifier, the second group of threads having an eligible instruction ready for execution that was not issued for instruction in the streaming multiprocessor during the issue cycle.