Java ™ 2: The Complete Reference, Fifth Edition

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Difference Between Dual Core and Core 2 Duo

Dual Core vs Core 2 Duo

Dual core processors are those that contain 2 cores in a single silicon chip while Core 2 Duo is the name given by Intel to its second batch of dual core processors.

The processor wars have hit a major speed bump as clock speeds become harder and harder to push upwards. Because the number of transistors in a single chip continues to follow its upward trend, processor manufacturers like Intel and AMD have decided to go a different route in increasing the performance of their products, adding more cores into a single chip that leads to a performance boost if the OS supports it. Two or more cores can greatly aid in multi-tasking where each core can work independently of each other. All processors that have 2 cores in them are collectively called as dual core processors regardless of which manufacturer it came from, while those that have 4 processors in a single chip are called quad core.

Initially, Intel called their dual core processors as Core Duo, a very obvious reference to two cores, while AMD called theirs the X2. Intel’s dual core processors were simply 2 Pentium 3 processors that were fabricated in a single chip. As they refined their product more, they decided to differentiate their second set of processors from the Core Duo and decided to call it Core 2 Duo.

Basically, the difference between dual core processors and the Core 2 Duo processors is just in the semantics as Core 2 Duo is simply a name given to a more recent family of dual core processors. If we translate this to the single core processors, we can say that Core Duo is Pentium 1 while Core 2 Duo is Pentium 2, while AMD has their own processors with different names; but all these are still single core processors. We can therefore say that Core 2 Duo is simply a subset of all the dual core processors that are out in the market today.

Summary:
1. Dual core is the generic name given to processors that have 2 cores on the same chip
2. Core 2 Duo is the second line of dual core processors from Intel
3. Other dual core processors aside from Core 2 Duo are the Core Duo from Intel and the X2 series from AMD
4. All Core 2 Duo processors are dual core but not all dual core processors are Core 2 Duo

Difference Between Pentium D and Pentium Dual Core

Pentium D vs Pentium Dual Core

The Pentium D was Intel ‘s first dual core processor as it strived to compete with AMD who already had a dual core processor out in the market. It had a lot of flaws and quickly superseded by the Pentium Dual core processor, which was released just a couple of years later. The difference between these two processors that dictate the other aspects is the architecture from which they were based from. The Pentum Ds were based on the P4 while the dual cores have adapted the core architecture that was later used by the Core and Core2 lines.

Generally, Pentium Ds are able to run at much higher clock speeds compared to the dual cores. Pentium Ds were able to reach speeds of up to 3.7Ghz while the dual cores stopped just over 3Ghz. Heat was holding the Pentium Ds back and even at lower clock speeds, it still produced a lot more heat compared to the dual cores. The Pentium Ds have a TDP of between 95-130W while the dual cores only had 65W TDP. As heat generated is correlated to how much power it consumes, we can correctly conclude that the Pentium D is also very power hungry, which is a very bad thing when you are looking at a laptop.

The design of the Pentium Ds was simply two P4 cores sitting side by side. They do not share anything and they basically work independently. With the dual cores, the L2 caches of the cores are shared. Along with the differences in architecture, the dual cores outperformed the Pentium Ds in all aspect while consuming lesser power and producing less heat. Overclockers also preferred the dual cores for the very same reason.

The better design of the dual cores proved to be the saving grace of Intel as AMD had them beat when it comes to the very weak and seemingly undercooked release of the Pentium Ds. For some time, AMD held the top spot in terms of retail sales due to the failure of the Pentium D.

Summary:

1. Dual cores are based on the core architecture while Pentium Ds are based on the P4

2. Dual cores run on a lower clock speed than the Pentium D

3. Dual cores produce less heat than the Pentium D

4. Dual cores consume less power than Pentium D

5. Dual cores have a shared L2 cache while Pentium Ds have a non-shared L2 cache

6. Dual cores outperform Pentium Ds

Supercomputer

 Supercomputer

"High-performance computing"

The Blue Gene/P supercomputer at Argonne National Lab runs over 250,000 processors using normal data center air conditioning, grouped in 72 racks/cabinets connected by a high-speed optical network

A supercomputer is a computer at the frontline of current processing capacity – particularly speed of calculation. The term "Super Computing" was first used in the New York World in 1929 to refer to large custom-built tabulators that IBM had made for Columbia University.

Supercomputers were introduced in the 1960s, designed initially and, for decades, primarily by Seymour Cray at Control Data Corporation (CDC), Cray Research and subsequent companies bearing his name or monogram. While the supercomputers of the 1970s used only a few processors, in the 1990s machines with thousands of processors began to appear and, by the end of the 20th century, massively parallel supercomputers with tens of thousands of "off-the-shelf" processors were the norm.^[2][3] As of November 2012, the Cray Titan supercomputer is the fastest in the world: at 17.6 PetaFLOPS, it is almost 20 billion (2 x 10¹⁰) times faster than the first supercomputer (the CDC 6600). For comparison purposes, that is the difference between the top speed of a common sloth vs. the speed of light in a vacuum.

Systems with massive numbers of processors generally take one of two paths: In one approach (e.g., in distributed computing), a large number of discrete computers (e.g., laptops) distributed across a network (e.g., the internet) devote some or all of their time to solving a common problem; each individual computer (client) receives and completes many small tasks, reporting the results to a central server which integrates the task results from all the clients into the overall solution. In another approach, a large number of dedicated processors are placed in close proximity to each other (e.g. in a computer cluster); this saves considerable time moving data around and makes it possible for the processors to work together (rather than on separate tasks), for example in mesh and hypercube architectures.

The use of multi-core processors combined with centralization is an emerging trend; one can think of this as a small cluster (the multicore processor in a smartphone, tablet, laptop, etc.) that both depends upon and contributes to the cloud.

Supercomputers play an important role in the field of computational science, and are used for a wide range of computationally intensive tasks in various fields, including quantum mechanics, weather forecasting, climate research, oil and gas exploration, molecular modeling (computing the structures and properties of chemical compounds, biological macromolecules, polymers, and crystals), and physical simulations (such as simulations of the early moments of the universe, airplane and spacecraft aerodynamics, the detonation of nuclear weapons, and nuclear fusion). Throughout their history, they have been essential in the field of counter-cryptography.

History

History of supercomputing

 

 

A Cray-1 preserved at the Deutsches Museum

 

The history of supercomputing goes back to the 1960s when a series of computers at Control Data Corporation (CDC) were designed by Seymour Cray to use innovative designs and parallelism to achieve superior computational peak performance.The CDC 6600, released in 1964, is generally considered the first supercomputer.

Cray left CDC in 1972 to form his own company.Four years after leaving CDC, Cray delivered the 80 MHz Cray 1 in 1976, and it became one of the most successful supercomputers in history.The Cray-2 released in 1985 was an 8 processor liquid cooled computer and Fluorinert was pumped through it as it operated. It performed at 1.9 gigaflops and was the world's fastest until 1990.

While the supercomputers of the 1980s used only a few processors, in the 1990s, machines with thousands of processors began to appear both in the United States and in Japan, setting new computational performance records. Fujitsu's Numerical Wind Tunnel supercomputer used 166 vector processors to gain the top spot in 1994 with a peak speed of 1.7 gigaflops per processor. The Hitachi SR2201 obtained a peak performance of 600 gigaflops in 1996 by using 2048 processors connected via a fast three dimensional crossbar network.The Intel Paragon could have 1000 to 4000 Intel i860 processors in various configurations, and was ranked the fastest in the world in 1993. The Paragon was a MIMD machine which connected processors via a high speed two dimensional mesh, allowing processes to execute on separate nodes; communicating via the Message Passing Interface.

Hardware and architecture

Supercomputer architecture and Parallel computer hardware

 

 

A Blue Gene/L cabinet showing the stacked blades, each holding many processors

 

Approaches to supercomputer architecture have taken dramatic turns since the earliest systems were introduced in the 1960s. Early supercomputer architectures pioneered by Seymour Cray relied on compact innovative designs and local parallelism to achieve superior computational peak performance.However, in time the demand for increased computational power ushered in the age of massively parallel systems.

While the supercomputers of the 1970s used only a few processors, in the 1990s, machines with thousands of processors began to appear and by the end of the 20th century, massively parallel supercomputers with tens of thousands of "off-the-shelf" processors were the norm. Supercomputers of the 21st century can use over 100,000 processors (some being graphic units) connected by fast connections.

Throughout the decades, the management of heat density has remained a key issue for most centralized supercomputers.The large amount of heat generated by a system may also have other effects, e.g. reducing the lifetime of other system components.There have been diverse approaches to heat management, from pumping Fluorinert through the system, to a hybrid liquid-air cooling system or air cooling with normal air conditioning temperatures.

 

 

The CPU share of TOP500

Systems with a massive number of processors generally take one of two paths: in one approach, known as grid computing, the processing power of a large number of computers in distributed, diverse administrative domains, is opportunistically used whenever a computer is available. In another approach, a large number of processors are used in close proximity to each other, e.g. in a computer cluster. In such a centralized massively parallel system the speed and flexibility of the interconnect becomes very important and modern supercomputers have used various approaches ranging from enhanced Infiniband systems to three-dimensional torus interconnects. The use of multi-core processors combined with centralization is an emerging direction, e.g. as in the Cyclops64 system.

As the price/performance of general purpose graphic processors (GPGPUs) has improved, a number of petaflop supercomputers such as Tianhe-I and Nebulae have started to rely on them.However, other systems such as the K computer continue to use conventional processors such as SPARC-based designs and the overall applicability of GPGPUs in general purpose high performance computing applications has been the subject of debate, in that while a GPGPU maybe tuned to score well on specific benchmarks its overall applicability to everyday algorithms may be limited unless significant effort is spent to tune the application towards it.However, GPUs are gaining ground and in 2012 the Jaguar supercomputer was transformed into Titan by replacing CPUs with GPUs.

A number of "special-purpose" systems have been designed, dedicated to a single problem. This allows the use of specially programmed FPGA chips or even custom VLSI chips, allowing better price/performance ratios by sacrificing generality. Examples of special-purpose supercomputers include Belle, Deep Blue, and Hydra,for playing chess, Gravity Pipe for astrophysics, MDGRAPE-3 for protein structure computation molecular dynamics and Deep Crack, for breaking the DES cipher.

Energy usage and heat management

Computer cooling and Green 500

A typical supercomputer consumes large amounts of electrical power, almost all of which is converted into heat, requiring cooling. For example, Tianhe-1A consumes 4.04 Megawatts of electricity.The cost to power and cool the system can be significant, e.g. 4MW at $0.10/kWh is $400 an hour or about $3.5 million per year.

 

An IBM HS20 blade

 

Heat management is a major issue in complex electronic devices, and affects powerful computer systems in various ways.The thermal design power and CPU power dissipation issues in supercomputing surpass those of traditional computer cooling technologies. The supercomputing awards for green computing reflect this issue.

The packing of thousands of processors together inevitably generates significant amounts of heat density that need to be dealt with. The Cray 2 was liquid cooled, and used a Fluorinert "cooling waterfall" which was forced through the modules under pressure.^[16] However, the submerged liquid cooling approach was not practical for the multi-cabinet systems based on off-the-shelf processors, and in System X a special cooling system that combined air conditioning with liquid cooling was developed in conjunction with the Liebert company.

In the Blue Gene system IBM deliberately used low power processors to deal with heat density.On the other hand, the IBM Power 775, released in 2011, has closely packed elements that require water cooling.The IBM Aquasar system, on the other hand uses hot water cooling to achieve energy efficiency, the water being used to heat buildings as well.

The energy efficiency of computer systems is generally measured in terms of "FLOPS per Watt". In 2008 IBM's Roadrunner operated at 376 MFLOPS/Watt. In November 2010, the Blue Gene/Q reached 1684 MFLOPS/Watt. In June 2011 the top 2 spots on the Green 500 list were occupied by Blue Gene machines in New York (one achieving 2097 MFLOPS/W) with the DEGIMA cluster in Nagasaki placing third with 1375 MFLOPS/W.

Software and system management

Operating systems

Supercomputer operating systems

Since the end of the 20th century, supercomputer operating systems have undergone major transformations, as sea changes have taken place in supercomputer architecture. While early operating systems were custom tailored to each supercomputer to gain speed, the trend has been to move away from in-house operating systems to the adaptation of generic software such as Linux.

Given that modern massively parallel supercomputers typically separate computations from other services by using multiple types of nodes, they usually run different operating systems on different nodes, e.g. using a small and efficient lightweight kernel such as CNK or CNL on compute nodes, but a larger system such as a Linux-derivative on server and I/O nodes.

While in a traditional multi-user computer system job scheduling is in effect a tasking problem for processing and peripheral resources, in a massively parallel system, the job management system needs to manage the allocation of both computational and communication resources, as well as gracefully dealing with inevitable hardware failures when tens of thousands of processors are present.

Although most modern supercomputers use the Linux operating system, each manufacturer has made its own specific changes to the Linux-derivative they use, and no industry standard exists, partly due to the fact that the differences in hardware architectures require changes to optimize the operating system to each hardware design.

Software tools and message passing

Message passing in computer clusters

Parallel computing and Parallel programming model

 

 

Wide-angle view of the ALMA correlator.

 

The parallel architectures of supercomputers often dictate the use of special programming techniques to exploit their speed. Software tools for distributed processing include standard APIs such as MPI and PVM, VTL, and open source-based software solutions such as Beowulf.

In the most common scenario, environments such as PVM and MPI for loosely connected clusters and OpenMP for tightly coordinated shared memory machines are used. Significant effort is required to optimize an algorithm for the interconnect characteristics of the machine it will be run on; the aim is to prevent any of the CPUs from wasting time waiting on data from other nodes. GPGPUs have hundreds of processor cores and are programmed using programming models such as CUDA.

Distributed supercomputing

Opportunistic approaches

Grid computing

 

 

Example architecture of a grid computing system connecting many personal computers over the internet

Opportunistic Supercomputing is a form of networked grid computing whereby a “super virtual computer” of many loosely coupled volunteer computing machines performs very large computing tasks. Grid computing has been applied to a number of large-scale embarrassingly parallel problems that require supercomputing performance scales. However, basic grid and cloud computing approaches that rely on volunteer computing can not handle traditional supercomputing tasks such as fluid dynamic simulations.

The fastest grid computing system is the distributed computing project Folding@home. F@h reported 8.1 petaflops of x86 processing power as of March 2012. Of this, 5.8 petaflops are contributed by clients running on various GPUs, 1.7 petaflops come from PlayStation 3 systems, and the rest from various CPU systems.

The BOINC platform hosts a number of distributed computing projects. As of May 2011, BOINC recorded a processing power of over 5.5 petaflops through over 480,000 active computers on the network The most active project (measured by computational power), MilkyWay@home, reports processing power of over 700 teraflops through over 33,000 active computers.

As of May 2011, GIMPS's distributed Mersenne Prime search currently achieves about 60 teraflops through over 25,000 registered computers.The Internet PrimeNet Server supports GIMPS's grid computing approach, one of the earliest and most successful grid computing projects, since 1997.

In 2012, Simon Cox made a supercomputer consisting of 64 Raspberry Pi units. The system was called Iridis-Pi. The whole system cost under £2,500 (excluding switches) and had a total of 1Tb of memory (16Gb SD cards for each Raspberry Pi).

Quasi-opportunistic approaches

Quasi-opportunistic supercomputing

Quasi-opportunistic supercomputing is a form of distributed computing whereby the “super virtual computer” of a large number of networked geographically disperse computers performs huge processing power demanding computing tasks.Quasi-opportunistic supercomputing aims to provide a higher quality of service than opportunistic grid computing by achieving more control over the assignment of tasks to distributed resources and the use of intelligence about the availability and reliability of individual systems within the supercomputing network. However, quasi-opportunistic distributed execution of demanding parallel computing software in grids should be achieved through implementation of grid-wise allocation agreements, co-allocation subsystems, communication topology-aware allocation mechanisms, fault tolerant message passing libraries and data pre-conditioning.

Performance measurement

Capability vs capacity

Supercomputers generally aim for the maximum in capability computing rather than capacity computing. Capability computing is typically thought of as using the maximum computing power to solve a single large problem in the shortest amount of time. Often a capability system is able to solve a problem of a size or complexity that no other computer can, e.g. a very complex weather simulation application.

Capacity computing in contrast is typically thought of as using efficient cost-effective computing power to solve a small number of somewhat large problems or a large number of small problems, e.g. many user access requests to a database or a web site.Architectures that lend themselves to supporting many users for routine everyday tasks may have a lot of capacity but are not typically considered supercomputers, given that they do not solve a single very complex problem.

Performance metrics

LINPACK benchmarks

 

 

Top supercomputer speeds: logscale speed over 60 years

In general, the speed of supercomputers is measured and benchmarked in "FLOPS" (FLoating Point Operations Per Second), and not in terms of MIPS, i.e. as "instructions per second", as is the case with general purpose computers. These measurements are commonly used with an SI prefix such as tera-, combined into the shorthand "TFLOPS" (10¹² FLOPS, pronounced teraflops), or peta-, combined into the shorthand "PFLOPS" (10¹⁵ FLOPS, pronounced petaflops.) "Petascale" supercomputers can process one quadrillion (10¹⁵) (1000 trillion) FLOPS. Exascale is computing performance in the exaflops range. An exaflop is one quintillion (10¹⁸) FLOPS (one million teraflops).

No single number can reflect the overall performance of a computer system, yet the goal of the Linpack benchmark is to approximate how fast the computer solves numerical problems and it is widely used in the industry.The FLOPS measurement is either quoted based on the theoretical floating point performance of a processor (derived from manufacturer's processor specifications and shown as "Rpeak" in the TOP500 lists) which is generally unachievable when running real workloads, or the achievable throughput, derived from the LINPACK benchmarks and shown as "Rmax" in the TOP500 list. The LINPACK benchmark typically performs LU decomposition of a large matrix. The LINPACK performance gives some indication of performance for some real-world problems, but does not necessarily match the processing requirements of many other supercomputer workloads, which for example may require more memory bandwidth, or may require better integer computing performance, or may need a high performance I/O system to achieve high levels of performance.

The TOP500 list

TOP500

 

 

Pie Chart of Supercomputer Countries Share as of Nov 2012

Since 1993, the fastest supercomputers have been ranked on the TOP500 list according to their LINPACK benchmark results. The list does not claim to be unbiased or definitive, but it is a widely cited current definition of the "fastest" supercomputer available at any given time.

This is a recent list of the computers which appeared at the top of the TOP500 list,and the "Peak speed" is given as the "Rmax" rating. For more historical data see History of supercomputing.

Year	Supercomputer	Peak speed (Rmax)	Location
2008	IBM Roadrunner	1.026 PFLOPS	Los Alamos, USA
		1.105 PFLOPS
2009	Cray Jaguar	1.759 PFLOPS	Oak Ridge, USA
2010	Tianhe-IA	2.566 PFLOPS	Tianjin, China
2011	Fujitsu K computer	10.51 PFLOPS	Kobe, Japan
2012	IBM Sequoia	16.32 PFLOPS	Livermore, USA
2012	Cray Titan	17.59 PFLOPS	Oak Ridge, USA

Sequoia was the world's fastest supercomputer at 16.32 petaflops, consuming 7890.0 kW, until October 29, 2012 when Titan went online.

Applications of supercomputers

The stages of supercomputer application may be summarized in the following table:

Decade	Uses and computer involved
1970s	Weather forecasting, aerodynamic research (Cray-1).
1980s	Probabilistic analysis,radiation shielding modeling(CDC Cyber).
1990s	Brute force code breaking (EFF DES cracker),
2000s	3D nuclear test simulations as a substitute for legal conduct Nuclear Proliferation Treaty (ASCI Q).
2010s	Molecular Dynamics Simulation (Tianhe-1A)

The IBM Blue Gene/P computer has been used to simulate a number of artificial neurons equivalent to approximately one percent of a human cerebral cortex, containing 1.6 billion neurons with approximately 9 trillion connections. The same research group also succeeded in using a supercomputer to simulate a number of artificial neurons equivalent to the entirety of a rat's brain.

Modern-day weather forecasting also relies on supercomputers. The National Oceanic and Atmospheric Administration uses supercomputers to crunch hundreds of millions of observations to help make weather forecasts more accurate.

In 2011, the challenges and difficulties in pushing the envelope in supercomputing were underscored by IBM's abandonment of the Blue Waters petascale project.

Research and development trends

 

 

Diagram of a 3 dimensional torus interconnect used by systems such as Blue Gene, Cray XT3, etc.

On November 7, 2011, Fujitsu announced a 23.2 petaflop follow up system for the K computer, called PRIMEHPC FX10. It will use the same 6 dimensional torus interconnect and only one SPARC processor per node.The Chinese government announced on October 31, 2012 that they are building a 100 petaflop supercomputer named Tianhe-2, slated for completion in 2015.

Given the current speed of progress, industry experts estimate that supercomputers will reach 1 exaflops (10¹⁸) (one quintillion FLOPS) by 2018. At the same time as their 100 petaflop announcement, China also stated plans to have a 1 exaflop supercomputer online by 2018. Using the Intel MIC multi-core processor architecture, which is Intel's response to GPU systems, SGI plans to achieve a 500 fold increase in performance by 2018, in order to achieve one exaflop. Samples of MIC chips with 32 cores which combine vector processing units with standard CPU have become available.The Indian government has also stated ambitions for an exaflop range supercomputer, which they hope to complete by 2017.

Erik P. DeBenedictis of Sandia National Laboratories theorizes that a zettaflop (10²¹) (one sextillion FLOPS) computer is required to accomplish full weather modeling, which could cover a two week time span accurately. Such systems might be built around 2030.

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