What does virtual memory do?

The functions of virtual memory: 1. Improve resource utilization; 2. Provide continuous address space; 3. Isolate access rights of different processes; 4. Support multi-tasking; 5. Implement dynamic memory management; 6. , Support large memory programs; 7. Provide caching mechanism; 8. Optimize memory fragmentation management; 9. Support inter-process communication; 10. Improve system stability. Detailed introduction: 1. Improve resource usage. When the number of processes increases, the memory resources required will increase accordingly, which may cause some programs to have no main memory space available, etc.

Virtual memory is a technology used to manage computer storage. It combines physical memory (RAM) and hard disk space to provide the operating system and applications with The program provides a unified memory management interface so that applications can access hard disk space just like RAM. The main functions of virtual memory include the following aspects:

1. Improve resource usage: When the number of processes increases, the memory resources required will increase accordingly. This may cause some programs to have no main memory space available. Virtual memory can simulate hard disk space into memory usage, thereby effectively improving resource usage.

2. Provide continuous address space: Each process has an independent memory space and believes that it has a continuous address space. However, in reality, physical memory is composed of multiple RAM blocks, and the address space of each process may not be contiguous. Virtual memory maps the address space of a process into physical memory through technologies such as paging to achieve address space continuity.

3. Isolate the access rights of different processes: Each process has its own virtual memory space and does not interfere with each other. The operating system implements the isolation of different processes through the virtual memory mechanism, protecting the data of each process from being accessed and modified by other processes.

4. Support multi-tasking: In a multi-tasking operating system, multiple applications run at the same time and switch tasks. Virtual memory can manage the memory space of different tasks so that each task can be executed independently without interfering with each other.

5. Implement dynamic memory management: The operating system can dynamically allocate and reclaim memory resources as needed. When there is insufficient memory space, the operating system can swap some data to the hard disk, thereby freeing up more memory space for other programs to use. When the data needs to be used again, the operating system can load it back into memory from the hard drive.

6. Support large memory programs: For some large applications or games, the memory space required may exceed the size of physical memory. Virtual memory solves the problem of large memory programs being unable to run by storing part of the data on the hard disk.

7. Provide caching mechanism: Virtual memory can save commonly used data in RAM, thereby speeding up access to these data. When this data is accessed, the operating system loads them into RAM and saves them back to the hard drive when needed.

8. Optimize memory fragmentation management: As the application executes, fragmentation may occur in the physical memory, causing some memory blocks to not be effectively utilized. Virtual memory can organize contiguous memory space and optimize memory fragmentation management by moving part of the data to the hard disk.

9. Support inter-process communication: Virtual memory can be used to implement inter-process communication (IPC). Through shared memory, different processes can access the same physical memory space to achieve data exchange and synchronization.

10. Improve system stability: In a multi-tasking operating system, when an abnormality in a process causes a memory leak or an infinite loop, system resources may be exhausted. Virtual memory can isolate the resource usage of different processes to a certain extent, thereby avoiding the exhaustion of system resources and improving system stability.

In short, virtual memory is one of the important technologies for computer storage management. It provides a unified memory management interface for the operating system and applications by combining physical memory and hard disk space. Virtual memory can improve resource utilization, provide continuous address space, isolate access rights of different processes, support multi-tasking, implement dynamic memory management, and support large-memory programs.

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