Question

Calculate speed up ratio for a four segment pipeline and draw the diagram in space-time domain for this pipeline, the time to perform .a sub operation in each segment is 20 ns for executing 100 tasks.

Answer 1

Answer:

Given-

Four stage pipeline is used

Delay of stages = 60, 50, 90 and 80 ns

Latch delay or delay due to each register = 10 ns

Part-01: Pipeline Cycle Time-

Cycle time

= Maximum delay due to any stage + Delay due to its register

= Max { 60, 50, 90, 80 } + 10 ns

= 90 ns + 10 ns

= 100 ns

Part-02: Non-Pipeline Execution Time-

Non-pipeline execution time for one instruction

= 60 ns + 50 ns + 90 ns + 80 ns

= 280 ns

Part-03: Speed Up Ratio-

Speed up

= Non-pipeline execution time / Pipeline execution time

= 280 ns / Cycle time

= 280 ns / 100 ns

= 2.8

Part-04: Pipeline Time For 1000 Tasks-

Pipeline time for 1000 tasks

= Time taken for 1st task + Time taken for remaining 999 tasks

= 1 x 4 clock cycles + 999 x 1 clock cycle

= 4 x cycle time + 999 x cycle time

= 4 x 100 ns + 999 x 100 ns

= 400 ns + 99900 ns

= 100300 ns

Part-05: Sequential Time For 1000 Tasks-

Non-pipeline time for 1000 tasks

= 1000 x Time taken for one task

= 1000 x 280 ns

= 280000 ns