What Is a Virtual Function?

Virtualization refers to virtualizing a computer into multiple logical computers through virtualization technology. Multiple logical computers are running on one computer at the same time, each logical computer can run a different operating system, and applications can run in independent spaces without affecting each other, thereby significantly improving the work efficiency of the computer.

Virtualization

Virtualization refers to virtualizing a computer into multiple logical computers through virtualization technology. Run multiple logical computers simultaneously on one computer, each logical computer can run a different operating system, and

The main purpose of virtualization is to simplify the IT infrastructure. It simplifies access to resources and resource management.

The consumer can be an end user,

Seems like all disruptive technologies,

As virtualization applications become more and more popular, simply analyze the advantages and disadvantages of several major virtualization vendors

Each virtualization method has its own advantages, and the choice depends on the user's situation. One group

A very important aspect of any virtualized environment is reducing the management and maintenance needs of dynamic and complex IT infrastructure. In addition,

Virtualization can be proven in many ways. It is not a separate entity, but a collection of patterns and technologies that provide the functionality required to support the logical representation of resources and the functionality required to present them to consumers of these resources through standard interfaces. These patterns are themselves repetitions of the various virtual forms introduced earlier.

Here are some patterns and techniques that are often used when implementing virtualization:

Multiple logical representations of a single resource

This model is one of the most widely used models of virtualization. It contains only one physical resource, but the logical representation it presents to consumers is as if it contains multiple resources. The consumer interacts with this virtual resource as if he were the only consumer, regardless of whether he is sharing the resource with other consumers.

Single logical representation of multiple resources

This pattern consists of multiple combined resources to represent these resources as a single logical representation that provides a single interface. Leveraging multiple less powerful resources to create powerful and rich

1.Using habits and feelings: A large number of scattered PCs in enterprises adopt centralized computing combined with virtualization technology for centralized management. It does provide a good solution for our enterprise. However, we know that computing resources are indispensable, but they exist in different locations. We cannot reduce them on the terminal or on the server. Assume that the computing resources of each of our desktops today are equivalent to (cpu dual-core 2.0 memory 2G). In this environment, the user experience that we have become accustomed to is transferred to the server. For the concurrency of 100 users, the server must provide 100X2X2 equal to 400 CPU The computing power and 200G of memory can meet the experience environment that users are accustomed to (the redundancy is not calculated). Then we calculate if our enterprise has 500 users, and if it is 1000 users. In fact, it is impossible for us to provide such computing power to our users, so from this one side, we must sacrifice the user experience. Secondly, each user has to go to the server to download the operating system it uses. The bandwidth pressure is huge. The more users there are, the more obvious this factor is, so this factor also needs to be considered by business management personnel. The user experience is not as good as before. Will it affect the work of IT staff?

2. Equipment and software compatibility: We are accustomed to plug-and-play peripheral devices. Will the new system affect daily work habits? If there is an impact, how can we avoid it? Does the workload of our IT managers increase or decrease, and does the efficiency increase or decrease? We need specific consideration from our business management personnel.

3. Cost: Every penny spent by the company will specifically consider the input-output ratio. A good management tool must be promoted, at least it can give the company more than double the benefits in a period of time. Centralized

Virtualization software solution

There are many limitations to software-only virtualization solutions. "Guest" operating systems are often virtual

Virtualization

A virtual machine monitor (VMM) communicates with the hardware, and the VMM determines its access to all virtual machines on the system. (Note that most processors and memory accesses are independent of the VMM, and the VMM is only involved when certain events occur, such as page faults.) In a software-only virtualization solution, the position of the VMM in the software suite is traditional. The location of the operating system, and the location of the operating system is the traditional location of the application. This additional communication layer requires binary conversion to simulate the hardware environment by providing interfaces to physical resources such as processors, memory, storage, graphics cards, and network cards. This conversion will inevitably increase the complexity of the system. In addition, guest operating system support is limited by the capabilities of the virtual machine environment, which can hinder the deployment of specific technologies, such as 64-bit guest operating systems. In software-only solutions, the increased complexity of the software stack means that these environments are difficult to manage, which increases the difficulty of ensuring system reliability and security.

Virtualized hardware solution

The virtualization technology of the CPU is a hardware solution. The CPU that supports the virtual technology has a specially optimized instruction set to control the virtual process. With these instruction sets, VMM will easily improve the performance, compared to the virtual implementation of software. Great distance

Virtualization

To improve performance. Virtualization technology can provide chip-based functions and improve software-only solutions with compatible VMM software. Because the virtualized hardware can provide a new architecture and support the operating system to run directly on it, there is no need for binary conversion, which reduces the related performance overhead, greatly simplifies the VMM design, and then enables the VMM to be written in accordance with common standards and performance. powerful. In addition, in pure software VMM, there is a lack of support for 64-bit guest operating systems. With the continuous popularization of 64-bit processors, this serious shortcoming has become increasingly prominent. The CPU's virtualization technology, in addition to supporting a wide range of traditional operating systems, also supports 64-bit guest operating systems.

Virtualization technology is a solution. The complete situation requires the support of the CPU, motherboard chipset, BIOS, and software, such as VMM software or some operating systems themselves. Even if only the CPU supports virtualization technology, the software with VMM will have better performance than a system that does not support virtualization technology at all.

The two major CPU giants Intel and AMD are trying their best to take the lead in the field of virtualization, but AMD's virtualization technology is several months behind Intel. Intel has been promoting Intel Virtualization Technology (Intel VT) virtualization technology in its processor product line since late 2005. Intel has released a series of processor products with Intel VT virtualization technology, including the desktop platform's Pentium 4 6X2 series, Pentium D 9X0 series and Pentium EE 9XX series, as well as some products in the Core Duo series and Core Solo series. And Xeon LV series, Xeon 5000 series, Xeon 5100 series, Xeon MP 7000 series and Itanium 2 9000 series on server / workstation platforms; meanwhile, most of Intel's next-generation mainstream processors, including Merom

Virtualization

Core mobile processors, Conroe core desktop processors, Woodcrest core server processors, and Itanium 2 high-end server processors based on Montecito cores will all support Intel VT virtualization technology.

And AMD has also released a series of processor products that support AMD Virtualization Technology (AMD VT) virtualization technology, including the Socket S1 interface of the Turion 64 X2 series and the Socket AM2 interface of the Athlon 64 X2 series and Athlon 64 FX series, etc. And most of AMD s next-generation mainstream processors, including the forthcoming Socket F interface Opteron, will support AMDVT virtualization technology.