Multi-tasking is divided into parallel and concurrent. The parallelity is a multitasking on the space, and it is merely a multitasking in time.
Process concept
The basic characteristics of the modern operating system are concurrent, shared. Allow multiple procedures with independent features to enter the main memory. In the multiprocessor system, it can be performed in parallel, in a single processor system, can be implemented.
The concept of the process: Process can be executed with other programs and a program of execution, and the basic unit of the system for resource allocation and scheduling.
The process has dynamic, parallelism, independence, and mutual restriction.
The process consists of three parts: block, process control block (PCB), and data blocks. Block: Describe the task data block that needs to be completed: including the data and workspace required for the program in execution - the first two is the basis of the static existence of the process, and the entity PCB of the process: includes the process of the process, resources Managing information and control information - is the dynamic characteristics of the process - the unique flag of the process. In general, the PCB structure of the process is all or partially resident in memory.
