Since Intel introduced the dual-core processor, the dual-core has rushed at us with overwhelming force. Major manufacturers have invested heavily in their dual-core computers, as if we have entered the dual-core era. The rapid popularization of dual-core computers has caused a huge impact on the current single-core computer market. With the continuous decline in the price of dual-core computers, single-core computers are gradually stretched, and prices have to continue to fall. Major manufacturers launched their own dual-core computers, but sentenced their own single-core computers to death. Everyone knows that computers are updated quickly, and many people are worried that they will be out of date immediately after buying them. The emergence of dual-core has naturally become a problem that puzzles consumers at present. Should I buy a dual-core or single-core computer now? Buying a single core is worried that it will be out of date tomorrow, and the price of buying a dual core is more expensive, so many consumers have taken a wait until the price of the dual core comes down. Perhaps this is also a reason why the computer market was weak during May Day this year. Let's discuss whether to buy a dual-core or single-core computer today!
Dual-core has been deeply rooted in people's hearts, but what is dual-core and what is its concept? Solve this mystery first!
What is a dual-core processor?
The so-called dual-core processor is simply to integrate two processor cores on a CPU substrate and connect the processor cores through a parallel bus. Dual-core is not a new concept, but the most basic, simplest and easiest CMP (Chip Multiprocessor) type. In fact, in the field of RISC processors, dual-core or even multi-core has already been realized. CMP was first proposed by Stanford University in the United States. The idea is to implement SMP (Symmetric Multiprocessing) architecture in one chip and execute different processes in parallel. As early as the end of last century, Hewlett-Packard and IBM had put forward the feasibility design of dual-core processors. In 200 1 year, IBM introduced the POWER4 processor based on dual-core, and then Sun and Hewlett-Packard successively introduced the UltraSPARC and PA-RISC chips based on dual-core architecture. But at this time, the dual-core processor architecture is still in the high-end RISC field, and not long ago, Intel and AMD successively launched their own dual-core processors, and dual-core really entered the mainstream X86 field.
The most important reason why Intel and AMD introduced dual-core processors is that the main frequency of the original ordinary single-core processors is difficult to improve and the performance has not made a qualitative leap. Because the frequency is difficult to improve, Intel had to announce plans to stop 4GHz products after releasing 3.8GHz products. However, AMD can't greatly improve after the actual frequency exceeds 2GHz, and 3GHz has become an insurmountable hurdle for AMD. It is in this case that in order to find new selling points, both Intel and AMD have raised the banner of dual-core.
Introduction of Intel Dual-Core Processor
Intel's current desktop dual-core processor is code-named Smithfield, which can basically be considered as integrating two Prescott cores adopted by Pentium 4 into the same processor. The two cores * * * share the front-end bus, and each core has an independent secondary cache of 1MB, which adds up to 2MB * *, but this is obviously different from the 2MB cache of Pentium 4 6XX series processors. However, because the two cores in the processor have independent caches, it is necessary to ensure that the cache information of each physical core must be consistent, otherwise there will be operational errors. For example, a = 1 is recorded in the memory data area of the system; If the first processor core reads and writes this data area and rewrites it to A = 0, then the cache of the second processor core must also be updated to A = 0, otherwise the data will be wrong in future operations. This process is the consistency of cache data, which means that dual-core processors need "arbiters" to coordinate. In order to solve this problem, Intel handed this coordination work to the North Bridge Chip (MCH or GMCH): when two cores need to update the data cached in the processor synchronously, they need to update it through the front-end bus and then through the North Bridge. Although the cached data is not huge, it will undoubtedly bring some delay because it needs to be processed through the north bridge, and the communication between cores will become slow, which will greatly affect the performance of the processor.
Intel's current desktop dual-core processor products are divided into two series: Pentium D and Pentium EE. Among them, Pentium D includes 820(2.8GHz), 830(3.0GHz) and 840(3.2GHz), which adopts 800MHz FSB and faces the mainstream market. At present, Pentium EE has only one 840(3.2GHz), which also uses 800MHz FSB for high-end applications. Pentium d and Pentium EE both adopt 0.09 micron process and LGA775 interface; The main difference between them is that Pentium EE supports Hyper-Threading Technology, while Pentium D does not support Hyper-Threading Technology, which means that when Hyper-Threading Technology is turned on, Pentium EE will be recognized as four processors by the operating system.
As for motherboard chipset, Northbridge chip plays an important role in cache data processing and exchange among different cores. At present, 945/955 series can support Pentium D and Pentium EE, but 9 15/925 can't. Even if you can boot on the 9 15/925 motherboard, you can only use one dual core!
Brief introduction of AMD dual-core processor
AMD's current desktop dual-core processors are code-named Toledo and Manchester. Basically, it can be simply regarded as integrating the two Venice cores adopted by Athlon 64 into the same processor. Each core has an independent L2 cache of 5 12KB or 1MB, and the two cores * * * enjoy Hyper Transport, which is basically the same as the current Athlon 64 architecture. However, unlike Intel's dual-core processor, AMD's Athlon 64 processor integrates a memory controller. Athlon 64 is designed for dual-core, but it still needs an arbiter to ensure the consistency of its cached data. AMD adopted SRQ (System Request Queue) technology here. At work, each core puts its request in SRQ, and when resources are obtained, the request will be sent to the corresponding execution core, so the consistency of its cached data can be completed directly in the processor without going through the Northbridge chip. Compared with Intel's dual-core processor, its advantage is that the delay of caching data is greatly reduced.
AMD's current desktop dual-core processor is Athlon 64 X2, and the models are divided into 3800+ to 4800+ according to the PR value. It also adopts 0.09 micron technology, Socket 939 interface, supports Hyper Transport at 65,438+0 GHz, and of course supports dual-channel DDR memory technology.
Because the arbiter of AMD dual-core processor is CPU instead of Northbridge chip, the choice of motherboard chipset is much looser than Intel dual-core processor, and it can even be said that it has nothing to do with motherboard chipset. Theoretically, any motherboard of Socket 939 can support Athlon 64 X2 by updating BIOS. For ordinary consumers, this can protect the existing investment, and there is no need to upgrade the motherboard at the same time as the Intel dual-core processor.
The following figure is a comparison photo of two Intel single-core and dual-core CPUs (the dual-core Pentium D 820 on the left and the single-core Pentium 4 670 on the right).
Do you really need a dual-core processor?
When the author asks many consumers what configuration of notebook computers they want to buy, most consumers are not sure what configuration can meet their needs. In fact, for this question, you can ask in reverse: "What did you buy a laptop for?" After changing the question, I believe most consumers can answer it, and 90% of the answers will focus on the following items: surfing the Internet, chatting, word processing, working, watching movies and playing games. If there are only these applications, do you really need to buy a dual-core processor?
In order to give you a more comprehensive understanding of dual-core processors, let's start with Centrino's second-generation SONOMA platform. Intel has adopted new technologies such as PCI Express, SATA (some models), DDR2 memory and dual channel on the SONOMA platform, but it is only "hyper-threading".
What is Hyperthreading? Generally speaking, it means that a processor can execute multiple programs at the same time and share resources in the same processor. Theoretically, a processor with hyper-threading technology can execute two instructions at the same time, while a processor without this technology can only run one instruction at any time. The problem came out again. Why doesn't Intel use Hyper-Threading Technology on Yonah processors? Hyper-threading technology can simulate two logical cores in a processor as two physical chips for multithreading operation, which reduces the idle time of CPU and improves the running efficiency of CPU, but it does not have independent resources like two real processors. When two threads need a resource at the same time, one of them has to stop temporarily and give up the resource until these resources are free. Therefore, the performance of hyper-threading is not equal to two CPUs, and the performance of the processor will also be reduced when encountering programs that do not support multiprocessor jobs. In addition, Hyper-Threading Technology needs the support of chipset and software to give full play to the advantages of this technology. In other words, hyper-threading technology is obviously "too much input and too little output".
On the other hand, Intel also urgently needs to improve the performance of the processor. Due to the limitation of manufacturing technology and high cost, the single-core Pentium M processor has reached the limit in frequency and cache. If we continue to blindly increase the working frequency, it will bring huge heat, which is very fatal to notebook computers. So it is inevitable to adopt dual-core processor on Napa platform.
The so-called dual-core processor is to integrate two physical processor cores into one core. In fact, the dual-core architecture is not a new technology, but the dual-core processor has always been the patent of the server, and now it has begun to penetrate into the PC.
Having said so much about Hyper-Threading and Dual-Core, I mainly want to make it clear that dual-core technology is actually to replace Hyper-Threading technology. As mentioned above, dual-core technology can actually be understood as two "physical" processors, which is a "hard" way; Hyper-threading technology is just two "logical" processors, which is a "soft" way. So the main advantage of dual-core processor is that it can handle multi-threads and multi-tasks. In addition, the integrated two physical cores can also improve the overall performance of the processor, making the performance of dual-core processors significantly better than that of single-core processors.
Although operating systems such as Windows XP-PRO currently support dual physical cores and four logical cores, this does not mean that all software is optimized for dual cores. Therefore, in many practical applications, the performance of dual-core is not outstanding. For example, when running some single-threaded tasks such as multimedia software, games and office software, although the execution efficiency of dual-core processors is indeed higher than that of single-core processors, it can't meet many people's expectations. This is because when the processor executes instructions, only one core is actually working, and the other core is basically idle. To put it mildly, it can't be used. Run several single-threaded tasks? If it's a relatively simple task, such as surfing the Internet while listening to songs, I'm afraid you won't think the dual-core processor will be much faster. However, if you are playing 3D games and processing audio or video at the same time, you can realize the advantages of dual-core, and the system runs much smoother than a single-core processor. Therefore, in order to make dual-core processors really work, unless some tasks with a large amount of calculation are run at the same time, for ordinary users, if daily applications are single-threaded, dual-core processors are indeed a bit extravagant.
So, which consumers are suitable for dual-core processors? The author thinks that dual-core processors are mainly suitable for consumers who need graphic image processing, such as Adobe Photoshop and 3D MAX. These softwares are all multithreaded programs. When dual-core processors execute multitasking and multithreading programs, the performance of dual-core processors is about 50%-70% higher than that of single-core processors with the same frequency, and even in some applications, the performance can be improved by almost 65,438+000%.
For dual-core processors, many consumers still have such a misunderstanding that its performance is twice that of single-core processors, and Intel seems to exaggerate the performance of dual-core processors in advertising. Compare it with the same core processor. Although the performance of Yonah dual-core processor is much better than that of Yonah single-core processor, due to technical reasons, at the same frequency, the performance is only about 1.5 times that of the latter.
Of course, with the strong introduction and gradual popularization of dual-core processors, there will be more and more general applications supporting multithreading in the future, and then dual-core processors will really play a role for ordinary users.
From this point of view, for ordinary consumers, single-core processors are enough to meet daily work and entertainment needs. The popularity of dual-core CPU is inevitable. Intel has decided to make the penetration rate of dual-core CPU reach more than 90% before 2007, but the most important thing is that computers are suitable for consumers. As long as the single core can meet your needs, the single core is still the first choice now. After all, the price is lower than that of dual-core, and under the impact of dual-core, the price of single-core computers may be lower this year, which surprises us. We are consumers, and price reduction is always a good thing, so we will wait and see!