Assignment 1 Task 2

Re: Assignment 1 Task 2

by Jan Laukemann -
Number of replies: 0
Hi Isabella,

for Task 2 we have a simple (imaginary) microarchitecture which we could draw similar to the port model of a CPU on slide 21-23 of slide set 3a:

  +-------------------------------------+
  |              Scheduler              |
  +-------------------------------------+
     0 |       1 |      2 |     3 |
       \/        \/       \/      \/ 
   +-------+ +-------+ +------+ +------+
   |  ADD  | |  MULT | |  LD  | |  ST  |
   +-------+ +-------+ +------+ +------+

You can see, the architecture supports superscalarity as multiple execution units (ADD, MULT, LD, ST) can run in parallel.
However, a single instruction still requires multiple pipeline steps, e.g., a single ADD instruction requires 6 cycles.
Each execution unit/port can retire 1 instruction per cycle at most (i.e., when the pipeline is constantly filled, they all have a throughput of 1 instr/cy), so the maximum throughput of our architecture is 4 instructions per cycle if all pipelines are always filled.

I hope this helps!