A graphics processing unit (“GPU”) is configured to interrupt processing of a first context and to initiate processing of a second context upon command so that multiple programs can be executed by the GPU. The CPU creates and the GPU stores a run list containing a plurality of contexts for execution, where each context has a ring buffer of commands and pointers for processing. The GPU initiates processing of a first context in the run list and retrieves memory access commands and pointers referencing data associated with the first context. The GPU's pipeline processes data associated with first context until empty or interrupted. If emptied, the GPU switches to a next context in the run list for processing data associated with that next context. When the last context in the run list is completed, the GPU may switch to another run list containing a new list of contexts for processing.