The General Approaches and Design Philosophies of the Pentium 4 and G4e

The drastic difference in pipeline depth between the G4e and the Pentium 4 reflects some very important differences in the design philosophies and goals of the two processors. Both processors try to execute as many instructions as quickly as possible, but they attack this problem in two different ways.

The G4e’s approach to performance can be summarized as “wide and shallow.” Its designers added more functional units to its back end for executing instructions, and its front end tries to fill up these units by issuing instructions to each functional unit in parallel. In order to extract the maximum amount of instruction-level parallelism (ILP) from the linear code stream, the ...

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