Comprehensive summary of os topics

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Glossary

concurrency: Refers to a processor processing multiple tasks at the same time.
parallel: Refers to multiple processors or multi-core processors processing multiple different tasks at the same time.
process: The basic unit of resource allocation, which is an instance of program execution.
thread: Thread, a lightweight process, is the smallest unit of program execution and an execution flow of a process.
deadlock: A phenomenon in which two or more processes wait for each other due to competition for resources during the execution process. If there is no external force, they will not be able to advance.
hunger: means that a low-priority process cannot access a required resource because there is a high-priority process accessing the resource.
critical section: A program fragment that accesses shared resources that cannot be accessed by multiple threads at the same time.
system overhead: Refers to the time and space spent running the operating system program to manage the system.
busy waiting: When a process is in its critical section, other processes trying to enter the critical section must continue empty loops in the entry section.
amount of signal: A special data structure defined by the kernel. The data type of its representation value is an integer, which is used to solve the problem of process synchronization.
reset: Relocation is the process of transforming the logical address space of the program into the actual physical address space in the memory, that is to say, the process of modifying the instructions and data in the target program when loading.
atomic operation: Refers to an operation that will not be interrupted by the thread scheduling mechanism. Once this operation starts, it will run until it ends.
buffer: It is divided into input buffer and output buffer. The former temporarily stores the data sent by the peripheral so that the processor can take it away; the latter is used to temporarily store the data sent by the processor to the peripheral.
Virtual Memory: It is a technology of computer system memory management, which makes the application think that it uses continuous available memory, but in fact, it is usually divided into multiple physical memory fragments, and some are temporarily stored on external disk storage. Data exchange when required.
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