1. An apparatus comprising: a datapath that operates to execute primitive operations; a plurality of control units, including a primary control unit and at least one auxiliary control unit, coupled to each other and to the datapath, to control the datapath to selectively execute a plurality of hierarchically organized primitive operations to effectuate execution of user instruction streams constituted with instructions of an instruction set architecture (ISA), each instruction of the ISA being implemented with one or more hierarchical organization units of said hierarchically organized primitive operations, and the primary control unit having primary responsibility for controlling the datapath including scheduling execution of said hierarchical organization units of said hierarchically organized primitive operations, with the at least one auxiliary control unit assisting the primary control unit in at least dynamic decision variable evaluations to determine execution flow among said hierarchical organization units of said hierarchically organized primitive operations.