When purchasing a computer, the CPU is the core factor that needs to be considered, which determines the performance level of the computer. CPU from the early single-core, to the current dual-core, multi-core. In addition to the number of cores, the CPU also has the number of threads. Let's explain the CPU-related knowledge:
Number of CPUs: the number of CPU chips
The number of CPU cores: refers to the number of cores physically, that is, there are several cores on the hardware. Example: Dual-core includes 2 relatively independent CPU core unit groups, and quad-core includes 4 relatively independent CPU core unit groups.
Number of threads : A logical concept, simply put, the number of simulated CPU cores. For example, a 2-thread CPU can be simulated by a number of CPU cores, that is, the single-core CPU is simulated as a function similar to a dual-core CPU. What we see from the Task Manager's Performance tab is two CPUs.
Just like the Intel Celeron G460 currently used is a single-core, dual-thread CPU; the Intel Core i3 3220 is a dual-core four-thread; the Intel Core i7 4770K is a quad-core and eight-thread; the Intel Core i5 4570 is a quad-core and four-thread. For a CPU, the number of threads is always greater than or equal to the number of cores. A core corresponds to at least one thread, but through hyper-threading technology, a core can correspond to two threads, which means that it can run two threads at the same time.
( Note: The concept of the number of CPU threads is only useful for Intel CPUs , because it is implemented through Intel Hyper-Threading Technology, which was first applied to Pentium4. If there is no Hyper-Threading Technology, one CPU core corresponds to one thread. So for AMD's For CPU, there is only the concept of the number of cores, not the concept of the number of threads. )
The reason why the CPU needs to increase the number of threads is the need for multitasking. The higher the number of threads, the more beneficial it is to run multiple programs at the same time, because the number of threads is equal to the number of tasks that the CPU can process in parallel at a certain moment. Therefore, the number of threads is a logical concept, which is simply the number of simulated CPU cores. A core corresponds to at least one thread, but Intel has a hyper-threading technology that can simulate a physical thread as two threads to fully utilize the CPU performance, that is, a core can have two or more threads.
Design decision, intel designed logical threads = 2 * physical cores for his x86, ibm's power8 is logical threads = 8 * physical cores
Hyper-Threading , hyperthreading
Multi-core CPUs are mainly divided into native multi-core and packaged multi-core.
Native multi-core refers to multi-core in the true sense. It was first proposed by AMD. Each core is completely independent and has its own front-side bus, which will not cause conflicts. Even under high load conditions, each core is completely independent. It can ensure that its performance is not greatly affected. Generally speaking, the native multi-core has strong pressure resistance, but it requires advanced technology, and each expansion of a core requires a lot of research and development time. Multi-core encapsulation is to encapsulate multiple cores directly. For example, Intel's early PD dual-core series directly encapsulates two single cores, but the two cores can only share one front-side bus. When the two cores are fully loaded, The two cores will compete for the front-side bus, resulting in a significant drop in performance. Therefore, the early PDs were labeled as "high-frequency and low-energy". To improve the performance of encapsulated multi-core, try to reduce performance loss under the high pressure of multi-tasking. It can continuously expand the overall size of the front-side bus to make up for the performance loss caused by multi-core competition for resources, but this can only make up for the lack of performance to a certain extent, which is still much worse than the native one, and the latter The cost is relatively high, and the advantage is that the development of multi-core is much faster than native.
The core (Die), also known as the core , is the most important part of the CPU. The raised chip in the center of the CPU is the core, which is manufactured from monocrystalline silicon with a certain production process. All calculations, receiving/storing commands, and processing data of the CPU are performed by the core. All kinds of CPU cores have a fixed logical structure , and logical units such as L1 cache , L2 cache , execution unit, instruction level unit and bus interface will have a scientific layout.
Dual cores should have two physical computing cores
HT technology is hyper-threading technology , a weapon that created a glorious era of PENTIUM 4. Although it was rated as a failed technology, it played a certain role in promoting P4. Dual-core processor is a brand-new processor category; HT The technology is to implement two logical processors in the processor, which is to make full use of processor resources. The dual-core processor integrates two physical cores, which is a dual-core processor in the actual sense.
多核心处理器（英语：Multi-core processor），又称多核心微处理器，是在单个计算组件中，加入两个或以上的独立实体中央处理单元（简称核心，英语：Core）。这些核心可以分别独立地运行程序指令，利用并行计算的能力加快程序的运行速度。只有两个核心的处理器，称为双核心处理器（dual-core processor）。“多核心”通常是对于中央处理器（Central Processing Unit，CPU）而论的，但是某些时候也指数字信号处理器（DSP）和系统芯片（SoC）。
通常，把将两个或更多独立处理器封装在一个单一集成电路（IC）中的方案称为多核心处理器；而封装在不同IC中的独立处理器形成的计算机系统被称为多处理器。
多核心处理器！=多处理器
多核心处理器可以在不将每个核心分别独立物理封装的情况下进行多任务处理（线程级并发处理（Thread-Level Parallelism，TLP），这种形式的TLP通常被认为是芯片级多处理）。
在Windows中，用cmd命令中输入“wmic”，在出现的新窗口中分别输入：
“cpu get Name”
“cpu get NumberOfCores”
“cpu get NumberOfLogicalProcessors”即可查看物理CPU数、CPU核心数、线程数。
如下图：
Name：表示物理CPU数
NumberOfCores：表示CPU核心数
NumberOfLogicalProcessors：表示CPU线程数
注释：VM虚拟机中的CPU选择的核心数实际是代表线程数。
输入“cpu get *”也可
2.在cmd命令中输入“systeminfo”，以下信息表示物理CPU有两个
