【 Weak current College 】 comprehensive understanding of the Intel CPU

In an existing computer programs by multiple threads of execution, the thread is a series of related instruction. Early in the personal computer era, most programs containing only a single thread. At the time of the operating system at a time can only be one such program is run. Because the system cannot handle two tasks at the same time, the next task must wait until the end of the last task processing, can be processed later operating system innovation introduces multitasking, so as to be able to suspend a process to run another program. By using this method to quickly switch program, the system can "look" to run multiple programs at the same time. However, the fact that the processor has run only a single thread.

In 2003, Intel's Xeon at home on the application of new technology: Hyper-Threading technology

Hyper-Threading technology is one of my CPU at the same time perform more procedures and to share a single CPU resources within, in theory, like two CPU at the same time as the execution of two threads, processors need to join a logical processing unit, and the rest as integer arithmetic unit (ALU), floating point unit (FPU), level 2 cache (L2Cache) remain unchanged, the section is being shared.

Although using Hyper-Threading technology can simultaneously execute two threads, but it's not like two real CPU, each CPU has independent of resources. When two threads at the same time requires a certain resource, one that you want to temporarily stop and yield the resources until these resource idle before continuing. So hyper-threading performance does not mean that the two CPU performance.

According to Intel benchmarks that have Hyper-Threading technology, using multiple threads write application can access up to 30% performance boost. More importantly, the two programs simultaneously on a run on the processor without having to switch back and forth (see Figure 1).

We can realize the benefits, when you run a great game, and the CPU usage is still not 100%, so the system can quickly in DOC document's Raiders, browser, search engines, and play your own cheat codes like music of the switch in the free Winamp.



However, Hyper-Threading technology performance boost from two execution threads sharing resource availability restrictions. As a result, since these shared resources between competing, Hyper-Threading technology cannot implement two separate processors processing throughput. If you want in a single chip to achieve better performance boost, the processor will need two separate kernel so that each thread can have their exclusive package execution resources.



This is not a single core processor supporting HT technology

We can see that when the CPU integer units, floating point unit is idle, and, in turn, floating-point unit, integer unit is idle, and, of course, this caused the CPU resources and waste, in order to solve this problem. HT HT technology appeared.

Supports Hyper-Threading of single core CPU

HT (Hyper-ThreadingTechnology) Hyper-Threading technology:

Because the CPU more integrates a logical processing unit, the more integrated logic processing unit can use another logical processing unit unused resources. In this way, at the same time, the CPU and can handle a integer arithmetic and a floating point operations. This greatly improved the situation before the waste of resources. Improved operating efficiency. This is hyper-threading technology



Of course, the new issue also was born, if at the same time only integer operations or only for floating-point arithmetic? this is the case, the CPU would not be able to enjoy the HT technology, only integer operations or only for floating-point operations, HT technology is ineffective.


Dual-core technology

So the issue mentioned above, how to improve this situation? OK, dual-core technology solves this problem


Dual-core processors because has two complete kernel, so while you can make two integers or two floating-point operations, this greatly improves system efficiency, thereby promoting the improvement of the system performance.

It is however, now back to single core processor encounters a problem, another element in a dual-core processor is still idle? someone said that a dual-core CPU is capable of supporting HT technology?

Supports Hyper-Threading technology, dual-core processor



This design the benefits are unprecedented and obvious, but the only downside is the higher manufacturing costs, so now with Hyper-Threading technology and dual core processors only in high-end Xeon PentiumEE and part have on. We know that the Pentium 4 processor supporting Hyper-Threading processor machines, supports multiple CPU WINDOWS will recognize the two CPUs. And support dual-core processing machines, WINDOWS will recognize the two CPUs that support Hyper-Threading technology and dual core processors, WINDOWS will recognize four CPUs! today's latest CPU, with 4 cores have four worker threads.

Intuitive understanding of solo, solo + HT, dual-core, quad-core