操作系统概念h04.ppt

Operating System Page * Solaris10线程模型 Operating System Page * Chapter 4: Threads Overview Multithreading Models Threading Issues Pthreads Windows XP Threads Linux Threads Operating System Page * Pthreads A POSIX standard (IEEE 1003.1c) API for thread creation and synchronization API specifies behavior of the thread library, implementation is up to development of the library Common in UNIX operating systems (Solaris, Linux, Mac OS X) Pthreads Operating System Page * Operating System Page * Windows XP Threads Implements the one-to-one mapping Each thread contains A thread id Register set Separate user and kernel stacks Private data storage area The register set, stacks, and private storage area are known as the context of the threads Operating System Page * Linux Threads Linux refers to them as tasks rather than threads Thread creation is done through clone() system call clone() allows a child task to share the address space of the parent task (process) Operating System Page * Assignments 4.3，4.4, 4.5, 4.7 4.3 Under what circumstances does a multithreaded solution using multiple kernel threads provide better performance than a single-threaded solution on a single-processor system? Answer: When a kernel thread suffers a page fault, another kernel thread can be switched in to use the interleaving time in a useful manner. A single-threaded process, on the other hand, will not be capable of performing useful work when a page fault takes place. Therefore, in scenarios where a program might suffer from frequent page faults or has to wait for other system events, a multi-threaded solution would perform better even on a single-processor system Operating System Page * 4.4 Which of the following components of program state are shared across threads in a multithreaded process? a. Register values b. Heap memory c. Global variables d. Stack memory Answer: The threads of a multithreaded process share heap memory and global variables. Each thread has its separate set of regist