HP-UX 11i Internals

Threading Models and HP-UX

Several threading models are utilized in modern operating systems (see Figure 4-3).

M x 1 threading allows for a single kernel-level thread per process. In the user space, a user-level scheduler may be employed to approximate the actions of a multithreaded environment. Programmers use user-space library routines to accomplish pseudo-scheduling and resource coordination. The library routines must monitor the individual user threads and context-switch if the current active thread is about to make a system call that would result in a blocking action. Once any of a process's user threads blocks on a call, the entire process is placed in a wait state. Keep in mind that from the perspective of the kernel, this is a single-threaded ...