In order to manage processes, the kernel must have a clear picture of what each process is
doing. It must know, for instance, the process’s priority, whether it is running on the CPU or
blocked on some event, what address space has been assigned to it, which files it is allowed to address, and so on. This is the role of the process descriptor , that is, of a task_struct type
structure whose fields contain all the information related to a single process. As the repository of so much information, the process descriptor is rather complex. Not only does it contain many fields itself, but some contain pointers to other data structures that, in turn, contain pointers to other structures.
