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Maximum speedup of O(log n)

Maximum speedup of O(n / ln n)

  • These “bounds” were based on runtime performance of applications and were not necessarily valid in all cases
  • They reinforced the computer industry’s hesitancy to “get into” parallel processing

3. parallel processors

The machines are the true parallel processors (also called concurrent processors)

These paralle machines fall into Flynn’s taxonomy classes of SIMD and MIMD systems

– SIMD: Single Instruction stream and Multiple Data streams

– MIMD: Multiple Instruction streams and Multiple Data streams

Simd overview

  • Single “control unit” computer and anarray of “computational” computers
  • Control unit executes control-flowinstructions and scalar operations and passes vector instructions to the processor array
  • Processor instruction types:

– Extensions of scalar instructions

Adds, stores, multiplies, etc. become vector operations executed in all processors concurrently

– Must add the ability to transfer vector and scalar data between processors to the instruction set -- attributes of a “parallel language”

  • SIMD Examples

Vector addition

C(I) = A(I) + B(I)

Complexity O(n) in SISD systems for I=1 to n do

C(I) = A(I) + B(I)

Complexity O(1) in SIMD systems

Matrix multiply

A, B, and C are n-by-n matrices

Compute C= AxB

Complexity O(n3) in SISD systems

n2 dot products, each of which is O(n)

Complexity O(n2) in SIMD systems

Perform n dot products in parallel across M the array

Image smoothing

– Smooth an n-by-n pixel image to reduce “noise”

– Each pixel is replaced by the average of itself

and its 8 nearest neighbors

– Complexity O(n2) in SISD systems

– Complexity O(n) in SIMD systems

Pixel and 8 neighbors

Mimd systems overview

  • MIMD systems differ from SIMD ones in that the “lock-step” operation requirement is removed
  • Each processor has its own control unit and can execute an independent stream of

instructions

– Rather than forcing all processors to perform the same task at the same time, processors can be assigned different tasks that, when taken as a whole, complete the assigned application

  • SIMD applications can be executed on an MIMD structure

– Each processor executes its own copy of the SIMD algorithm

  • Application code can be decomposed into communicating processes

– Distributed simulations is a good example of a

very hard MIMD application

  • Keys to high MIMD performance are

– Process synchronization

– Process scheduling

  • Process synchronization targets keeping all processors busy and not suspended

awaiting data from another processor

  • Process scheduling can be performed

– By the programmer through the use of parallel language constructs

Specify apriori what processes will be instantiated and where they will be

executed

– During program execution by spawning processes off for execution on available processors.

Fork-join construct in some languages

  • System examples

SIMD

– Illiac IV

One of the first massively parallel systems 64 processors

– Goodyear Staran: 256 bit-serial processors

– Current system from Cray Computer Corp.uses supercomputer (Cray 3) front end coupled to an SIMD array of 1000s of processors

MIMD

– Intel hypercube series:

Supported up to several hundred CISC processors

Next-gen Paragon

– Cray Research T3D

Cray Y-MP coupled to a massive array of Dec Alphas

Target: sustained teraflop performance

4. discussions

  • Problems

– Hardware is relatively easy to build

– Massively parallel systems just take massive amounts of money to build

– How should/can the large numbers of processors be interconnected

– The real trick is building software that will exploit the capabilities of the system

  • Reality check:

– Outside of a limited number of high-profile applications, parallel processing is still a“young” discipline

– Parallel software is still fairly sparse

– Risky for companies to adopt parallel strategies, just wait for the next new SISD system.

Questions & Answers

Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
hi
Loga
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
with the given example MOV BX,AX describe the sequence that will be followed using instruction state diagram
Gireesh 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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