Lessons learned from dataflow (Continued)
- the decoupling of the instruction window with respect to different instruction classes,
- the partitioning of the issue stage into several pipeline stages,
- and alternative instruction window organizations.
Alternative instruction window organization: the dependence-based microprocessor:
- Instruction window is organized as multiple FIFOs.
- Only the instructions at the heads of a number of FIFO buffers can be issued to the execution units in the next cycle.
- The total parallelism in the instruction window is restricted in favor of a less costly issue that does not slow down processor cycle rate.
- Thereby the potential fine-grained parallelism is limited ? somewhat similar to the threaded dataflow approach.