基于ARM的智能手设备MP3播放器的设计与开发 英文参考文献.docVIP

（ Process Management The process is one of the fundamental abstractions in Unix operating systems. A process is a program(object code stored on some media) in execution. Processes are, however, more than just the executingprogram code (often called the text section in Unix). They also include a set of resources such as open files and pending signals, internal kernel data, processor state, an address space, one or more threads ofexecution, and a data section containing global variables. Processes, in effect, are the living result of running program code. Threads of execution, often shortened to threads, are the objects of activity within the process. Each thread includes a unique program counter, process stack, and set of processor registers. The kernel schedules individual threads, not processes. In traditional Unix systems, each process consists of one thread. In modern systems, however, multithreaded programsthose that consist of more than one threadare common. Linux has a unique implementation of threads: It does not differentiate between threads and processes. To Linux, a thread is just a special kind of process. On modern operating systems, processes provide two virtualizations: a virtualized processor and virtual memory. The virtual processor gives the process the illusion that it alone monopolizes the system, despite possibly sharing the processor among dozens of other processes. discusses this virtualization. Virtual memory lets the process allocate and manage memory as if it alone owned all the memory in the system. Interestingly, note that threads share the virtual memory abstraction while each receives its own virtualized processor. A program itself is not a process; a process is an active program and related resources. Indeed, two or more processes can exist that are executing the same program. In fact, two or more processes can exist that share various resources, such as open files or an address space. A process begins its life when,