The Gateway to Computer Science Excellence
0 votes
90 views
Considering a single CPU and 4 stages of pipeline

Now after some time Instruction fetch,Instruction Decode,Execute,Store is running parellely means overlapping . Thats why we are getting one instructions executed per clk cycle.[ideally]

Now my doubt is how pipeline stage overlapping is possible with single cpu. As all stages may need CPU inorder to perform their task.

Thanks
in CO and Architecture by Boss (23.9k points) | 90 views
0
The CPU design such a way such that more than one operation can done in same time. The only requirement of pipeline to reducing the processing time. That is why we can do overlapping the process and even out of order execution of stages is also accessable.

1 Answer

+2 votes
Best answer

A processor (a core) is not a different entity.For example this above 5 stage pipeline datapath is built inside a typical processor which enables the system to run overlapping instruction. The control unit synchronizes all stage operations. On a particular common clock pulse the control unit activates control signals and depending on which each stage do it's functionality. Make sure that here, the processor is not fetching more than one instrutions simultaneously.(superscalar processor is irrelevent in our case).

by Veteran (57.2k points)
selected by
0
Not fetches more than one instruction, but out of order execution of different stages is possible
0

out of order instruction is ok! Please tell little bit about stage out of order ?

I- I2 - I3 say these three are currently in the pipeline. Ientered first,Isecond and I3 last.

You mean I2 can complete its execution before I1 does. right ?

0
When we are telling about out of order instruction, a instruction can go previous than other instruction. even it is possible that some part of instruction go before another instruction. Until an external interrupt happens, it is fine. When an exception occured, the pipeline stops that instruction from executing. And all pending instruction must be complete first, then again it return back to that instruction.

No related questions found

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true
50,737 questions
57,385 answers
198,557 comments
105,368 users