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Let’s say that you are fast asleep some night and begin dreaming. In your dream, you have a time machine and a few 500-MHz four-way superscalar processors. You turn the time machine back to 1981. Once you arrive back in time, you go out and purchase an IBM PC with an Intel 8088 microprocessor running at 4.77 MHz. For much of the rest of the night, you toss and turn as you try to adapt the 500-MHz processor to the Intel 8088 socket using a soldering iron and Swiss Army knife. Just before you wake up, the new computer finally works, and you turn it on to run the Linpack See [link] Chapter 15, Using Published Benchmarks, for details on the Linpack benchmark. benchmark and issue a press release. Would you expect this to turn out to be a dream or a nightmare? Chances are good that it would turn out to be a nightmare, just like the previous night where you went back to the Middle Ages and put a jet engine on a horse. (You have got to stop eating double pepperoni pizzas so late at night.)

Even if you can speed up the computational aspects of a processor infinitely fast, you still must load and store the data and instructions to and from a memory. Today’s processors continue to creep ever closer to infinitely fast processing. Memory performance is increasing at a much slower rate (it will take longer for memory to become infinitely fast). Many of the interesting problems in high performance computing use a large amount of memory. As computers are getting faster, the size of problems they tend to operate on also goes up. The trouble is that when you want to solve these problems at high speeds, you need a memory system that is large, yet at the same time fast—a big challenge. Possible approaches include the following:

  • Every memory system component can be made individually fast enough to respond to every memory access request.
  • Slow memory can be accessed in a round-robin fashion (hopefully) to give the effect of a faster memory system.
  • The memory system design can be made “wide” so that each transfer contains many bytes of information.
  • The system can be divided into faster and slower portions and arranged so that the fast portion is used more often than the slow one.

Again, economics are the dominant force in the computer business. A cheap, statistically optimized memory system will be a better seller than a prohibitively expensive, blazingly fast one, so the first choice is not much of a choice at all. But these choices, used in combination, can attain a good fraction of the performance you would get if every component were fast. Chances are very good that your high performance workstation incorporates several or all of them.

Once the memory system has been decided upon, there are things we can do in software to see that it is used efficiently. A compiler that has some knowledge of the way memory is arranged and the details of the caches can optimize their use to some extent. The other place for optimizations is in user applications, as we’ll see later in the book. A good pattern of memory access will work with, rather than against, the components of the system.

In this chapter we discuss how the pieces of a memory system work. We look at how patterns of data and instruction access factor into your overall runtime, especially as CPU speeds increase. We also talk a bit about the performance implications of running in a virtual memory environment.

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.
yes that's correct
I think
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
How we are making nano material?
what is a peer
What is meant by 'nano scale'?
What is STMs full form?
scanning tunneling microscope
how nano science is used for hydrophobicity
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
what is differents between GO and RGO?
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
analytical skills graphene is prepared to kill any type viruses .
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
The nanotechnology is as new science, to scale nanometric
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
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
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, High performance computing. OpenStax CNX. Aug 25, 2010 Download for free at http://cnx.org/content/col11136/1.5
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