Windows XP An Overview.ppt

Windows XP: An Overview Brett O’Neill CSE 8343 – Group A6 Overview Programs, Processes, Jobs and Threads Registry and Memory File System Architecture and Management Inter-Process Communication Questions? References Processes Threads Windows XP process architecture is the same as Windows 2000 process architecture There are 4 units of work – Processes, Threads, Jobs and Programs. Simple definitions: Program – A static set of instructions Process – A container for a set of threads that execute an instance of a program Job – A group of processes that can be manipulated as a single unit Thread – A container for the set of instructions to be executed and the contents of machine registers that define processor state Processes Threads Each process includes a private virtual address space, an executable program, a list of open handles to various system resources, a security context, a unique identifier, and at least one thread. Processes Threads Fields in a Windows XP Executive Process (EPROCESS) Block: Processes Threads Each thread contains a set of instructions to execute, the contents of machine registers that define the processor state while the thread is running, and two stacks – one for User mode and one for Kernel mode. Processes Threads Fields in a Windows XP Executive Thread (ETHREAD) Block: Thread Scheduling Priority-driven, preemptive scheduling is used. Priorities levels are determined by both the process and the thread. Processes have 4 priority levels: Idle – Screen savers other display updates Normal – The default priority class High – Receive most of the CPU’s time Real Time – Kernel processes Thread Scheduling The process’s priority class sets a range of priority values for its threads. For example, Real Time processes will always have a value from 16-31. Process Priority Classes with Relative Thread Priorities: Thread Scheduling Threads run for a length of time known as a quantum. Quantum values vary from thread to thread. Threads do not neces