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In general, the time delay d is equivalent to a clock pulse and T m size 12{T rSub { size 8{m} } } {} >>d. Suppose that n instruction are processed with no branched.

  • The total time required T k size 12{T rSub { size 8{k} } } {} to execute all n instruction is:

T k size 12{T rSub { size 8{k} } } {} = [k + (n-1)]

  • The speedup factor for the instruction pipeline compared to execution without the pipeline is defined as:

S K = T 1 T K = nk τ k + ( n 1 ) τ = nk k + ( n 1 ) size 12{ { size 24{S} } rSub { size 8{K} } = { { { size 24{T} } rSub { size 8{1} } } over { { size 24{T} } rSub { size 8{K} } } } = { { ital "nk"τ} over { left [k+ \( n - 1 \) right ]τ} } = { { ital "nk"} over {k+ \( n - 1 \) } } } {}

  • An ideal pipeline divides a task into k independent sequential subtasks

– Each subtask requires 1 time unit to complete

– The task itself then requires k time units tocomplete. For n iterations of the task, the execution times will be:

– With no pipelining: nk time units

– With pipelining: k + (n-1) time units

Speedup of a k-stage pipeline is thus

S = nk / [k+(n-1)] ==>k (for large n)

2.2 pipeline limitations

Several factors serve to limit the pipeline performance. If the six stage are not of equal duration, there will be some waiting involved at various pipeline stage. Another difficulty is the condition branch instruction or the unpredictable event is an interrupt. Other problem arise that the memory conflicts could occur. So the system must contain logic to account for the type of conflict.

  • Pipeline depth

- Data dependencies also factor into the effective length of pipelines

- Logic to handle memory and register use and to control the overall pipeline increases significantly with increasing pipeline depth

– If the speedup is based on the number of stages, why not build lots of stages?

– Each stage uses latches at its input (output) to buffer the next set of inputs

+ If the stage granularity is reduced too much, the latches and their control become a significant hardware overhead

+ Also suffer a time overhead in the propagation time through the latches

- Limits the rate at which data can be clocked through the pipeline

  • Data dependencies

– Pipelining must insure that computed results are the same as if computation was performed in strict sequential order

– With multiple stages, two instructions “in execution” in the pipeline may have data dependencies. So we must design the pipeline to prevent this.

– Data dependency examples:

A = B + C

D = E + A

C = G x H

A = D / H

Data dependencies limit when an instruction can be input to the pipeline.

  • Branching

One of the major problems in designing an instruction pipeline is assuring a steady flow of instructions to initial stages of the pipeline. However, 15-20% of instructions in an assembly-level stream are (conditional) branches. Of these, 60-70% take the branch to a target address. Until the instruction is actually executed, it is impossible to determin whether the branch will be taken or not.

- Impact of the branch is that pipeline never really operates at its full capacity.

– The average time to complete a pipelined instruction becomes

Tave =(1-pb)1 + pb[pt(1+b) + (1-pt)1]

– A number of techniques can be used to minimize the impact of the branch instruction (the branch penalty).

- A several approaches have been taken for dealing with conditional branches:

+ Multiple streams

+ Prefetch branch target

+ Loop buffer

Questions & Answers

do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
Do somebody tell me a best nano engineering book for beginners?
s. Reply
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
good afternoon madam
what is system testing
what is the application of nanotechnology?
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
anybody can imagine what will be happen after 100 years from now in nano tech world
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Computer architecture. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10761/1.1
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