Advanced Computer Architecture, Imperial College 2001
3
Why add another processor?
•Increasing the complexity of a single CPU leads to diminishing returns
–Due to lack of instruction-level parallelism
–Too many simultaneous accesses to one register file
–Forwarding wires between functional units too long - inter-cluster communication takes >1 cycle
Number of transistors
Text Box: performance
performance
Smallest working CPU
Further simultaneous instruction issue slots rarely usable in real code