Dualcore Processors Technology

By: Mojtaba Sadeghi

Introduction:

When we are talking about dualcore processors , this question will appear in our mind that : What is the benefit of using from Dualcore processors? And With the growing of using of dual core processors, this question is more important than before. Will dual core processor be more useful for us?what is the advantages and disadvantages
of using dualcore processors? and what are the differences between Dualcore and dual processors?INTEL and AMD technology in dual core micro architecture. Which one is better?
I want to attempt in this paper to answer to these questions.

Definition of DualCore and compare with Dual Processor:

one of question for some users that they want to buy a high configuration system is if they want to have two processors in their computers. For video editing, huge graphic processing, multi-threading in applications, or a lot of multitasking the answer is positive. Then the second question becomes here: two separate processors or a single dual core processor ? Dual processor or Dual core ,which one is better for me?As we know computer manufacturers are trying to increasing the speed of processors.
However, size of duo, complexity and heat issues it has become increasingly difficult to make CPUs faster. To continue to improve performance, they reached to another solution. because having two Processors and of course one mainboard that support of hosting them is more expensive. Computer Architecture engineers created another
way: Using two Processors, Join them together in one chip. It can have the power and performance of two Processors but only one socket on the motherboard there is. This price will be cheaper , and allows for the power of two cores with a cost that is less than two separate Processors.
There are differences between brands mostly Intel and AMD that how they combined two cores in one chip, and the speeds they run each core that can directly affect how much is the performance from having a dual core Processor. Additionally, different types of programs get differing benefits and they use different types from dual core Processor that we will discuss about that in this research.
A dual core processor is exactly what that we say. It is two processor cores on one die
and like a dual processor system in one processor. AMD's Opteron processor has been
dual processor capable since started. Opteron was designed with an extra HyperTransport link that we will discuss about that. HyperTransport Technology means a faster data connection that it can to transfer more data between two chips. It
doesn't mean that the chip is faster by itself. It means this technology gives capability via the HyperTransport pathway for one chip to communication to another part.
As I explained a Dualcore Processor is a combination of two independent processors in a single package or a single integrated circuit (IC). A Dual Processor device contains two independent microprocessors and a quad core device contains four microprocessors as well. Cores in a Dualcore Processors will share a single coherent cache at the highest cache level that we say L2 Level cache, or may have
separate caches like current AMD dual-core processors. Each "core" independently
implements optimizations like: Fetching, Decoding, execution, pipelining, and
multithreading. A system with N cores is very useful when we have N or more threads at the same time . The technology is used in other technology areas in these days, especially those of embedded processors such as network processors In these
applications, multi-core processors with higher numbers of processing elements is using these days.

Section 2: Multi Processing

As a remind Multiprocessing is the using of two or more Processors in a computer system. OF course one of important issue is the ability of system for support more than one processor and the ability to allocate and divide the tasks between them.
Multiprocessing sometimes refers to the execution of various concurrent program processes in a system. However multiprogramming is very suitable to describe this concept, which is usually implemented in software, but multiprocessing is involve to describe the use of multiple Processors. Totally a system can be multiprocessing and multiprogramming , only one of them, or neither of them.

Section 3: Multi Thread Scheduling

One of question in Dualcore research is really how a computer knows when to use each core.The answer is that Operating system is responsible,because There is a part in the operating system that we call "scheduler" . Scheduler will order the Processor that which program should run at any time. This allows different programs can run at the same time, and processor can switch back between them if needed. When a lot of programs are running at the same time , a computer seems slow. If a dual-core
processor be available , the scheduler has twice Processor resource to work with that.
Normally this allows for some abilities like being able to run one core specifically for
a game, while using the other core to "background" things that keep the rest of the
system running. And sometimes both cores can work on the same program ,but if it designed to use advantage of dualcore that we call "multi-threaded". However, it is important to note that if you are running a program and it is not "multi-threaded", you will not get any benefit from more than one Processor or core.
Micro architecture of Processor resources divide to three types:
Replicated,Partitioned and shared.

Section 4 : Development

While manufacturing technology continues to improve, reducing the size of single gates become as a important issue. Some of this changing and physical limitations can create significant heat dissipation and data synchronization problems. The demand for more capable microprocessors with more efficiency causes CPU designers to use various methods of increasing performance. Some instruction-level parallelism (ILP) methods like pipelining are suitable for many applications, but they are not suitable for others. Many applications and programs are used to thread level parallelism(TLP) methods, and multiple independent CPUs is one method used to increase a system's overall TLP. Increasing available space due to refined manufacturing processes and the demand for increased TLP are the most logic behind the creation of Dualcore Procesors.

Section 5: Two cores versus Sole core

There are three important definition and term that I want to explain about them in my
paper .pipeline, cache and bus. This is the most explanations of what is pipelining in CPU .
First we should know the data instruction set. A processor loads the instructions into a pipeline.It means The data will process sequentially one set after another set.
Shorter pipeline means that more job will be perform in pipeline per clock cycle.
However with a shorter pipeline the data will get faster balancing that is very important as well.This is the main reason that AMD can compete with higher clock INTEL processors.
If the processor needs to access and communicate with outside of the cache ,it should be through the bus to system RAM. Now if the CPU cache is running at the same clock speed as the processor itself. If it is a 3GHz processor then the speed limitation between cache and the processor is 3GHz. If the processor has to communicate and
reach out of the bus to main memory then it should comes slow down to that bus speed. I mean a bus speed of 600 MHz is five times slower than the 3GHz .

Section 6: Implementation

There are different ways between AMD and Intel dual-core technology. AMD claims that they had this plan the move to dual-core from 6 years ago.from that time the first Athlon64 and Opteron released. The benefit of the AMD technology is in the way that the two cores will communicate directly with each other. Intel in another side, put two of Pentium cores on the same chip, and if they need to communicate
with each other it has to perform through the mainboard.another issue is that Intel did not increase the speed of FSB or front-side-bus that as we know is the connection between the Processor and the mainboard.It shows they
switched to dual-core and it means that the processing power did double but the amount of bandwidth for each core did not. This issue a little create suspect on the Intel design, and some users believe that Intel prevents it from being as powerful as it can be. But Intel Designers continue to use faster system memory to keep information supplied to the processor cores. For example the highest-end Intel chip,
the Pentium Extreme Edition 955chip , it has a higher FSB speed, as well as having a larger 2MB per core cache memory and the ability to use Hyperthreading.
On the other hand AMD Company, didn't use the old model of FSB. They use a new technology that we call HyperTransport to communicate with the Chipset and system memory, and they also moved the memory controller from the chipset to the
processor. By this new technology , AMD arrived to many advantage, especially with the move to dual-core processors. The latest generation of AMD solo core processor can use single channel or dual channel memory, but we should consider to that even though dual channel operation will double the memory speed, but it does not double
the actual memory performance for solo core processors. It shows that dual channel memory just provides more bandwidth than a solo processor core can use. However, with dual core processor all the extra bandwidth can be use.

Section 7: Advantages

In dual Processors at the same die have the cache coherency circuitry can that operate
much higher clock rate than is possible if the signals have to travel off-chip. It means
combining Two processors on a single die improves the performance of cache snoop or cache searching operations. That means the signals between different Processors travel shorter distances, those signals degrade less. These higher quality signals allow more data send and recieve in a specific time since individual signals can be shorter and do not need to repeat them.
Another issue is power consumption in hardware. A dualcore processor uses less power than two single-core processors or dual processors. The reason is that for increasing power required to drive signals external to the chip and because the smaller silicon process allows the cores to operate in lower voltages. The cores share some
circuitry, like the L2 cache and the interface to the front side bus (FSB).

Section 8: Disadvantages

As we learnt in Operating system and Computer Architecture totally Operating Systems try the best t use from available hardware for running the programs with maximize utilization mostly about Processor and RAM. Also, the ability of Dualcore processors to increase Software performance but it depends on the use of multiple
threads in application or program. For example, most of new video games will run faster on a 3 GHz singlecore processor than on a 2GHz dualcore processor in the the same core architecture. Because they are not capable of using more than one core at a time.
Another issue is about thermal. In a Dualcore Processor is more difficult to manage thermal than lower-density single chip processors. From an architectural point of view we can say sole core processor designs might be make better use of the silicon surface area than Dual processor design.in fact Two processing cores sharing in the same system bus and memory bandwidth will limit the real-world performance advantage. If a single core is close to being memory bandwidth limited, change to dual-core may only gives 30% to 65% improvement. And If memory bandwidth
doesn't make any problem, till 90% improvement can be expected. It would be possible for a software or application that use from two processors for running faster on one dualcore processor if communication between the Processor was the limited by factor, which would count as more than 100% improvement.

Section 9: Power Consumption

As we know the policy of Intel company is to design not only fast processors but also very economical processors when they were attemping on the new Core architecture.
Therefore, they started new activity base on performance-per-watt. That's why it is
interesting to look the power consumption of the new processors and compare it to the previous-generation processors based on older architecture.
For better conclusion I found a special utility to measure the maximum power consumption .It measured the current that goes through the CPU power circuitry. First , It measured the processors power consumption in idle mode.
The results are very diverse, as you can see, which is probably caused by too different
processor models participating. However, generally speaking, Core 2 Duo processors
can really boast the most economical performance in idle mode.

Section 10: Integral Characteristics of the Dual-Core Processors

Now I want to conclude my analysis of the new Intel processors performance and their features with those of other currently available dual-core CPUs with details for parameters that are indirectly connected with the performance rate.
For this reason , I decided to put an average performance chart for testing . We calculated this parameter as geometric mean of all normalized results obtained during this test session.
As we can see this chart again shows the better performance of the new Intel CPUs.
Athlon 64 Fx-62, can only compete with Core 2 Duo E6600, while Pentium Extreme Edition 965 cannot do competition even with Core 2 Duo E6400. From the performance view, Core 2 Extreme X6800, Core 2 Duo E6700 and Core 2 Duo E6600 on Intel Core microarchitecture won in this comparation.

Conclusion:

Actually we have made the most important conclusions about the performance,pricing and power consumption of DualCore Processors in this research. I just want to say once again that Intel company really did a great and excellent job with these processors on Core micro architecture.of course I don't want to say that AMD lost this competition and market in the world. This company managed with different way
and policy for their technology and products.and as we know AMD let Intel take the high-end market, but the cheaper price of AMD causes the are still remind as a powerfull competitor for intel.Ans also let me say that Pentium D processor family that has lost quite a few of its
members will still remain in demand. Despite the high over heating and power consumption of the models in this family, they will still be a good choice for inexpensive or home systems.
As you can see, the move to dual-core is definitely a win for consumers. Since they
are more economy than dual processor computers, and they can give the same or better performance. It can be the standard for modern computer systems.

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