Operating Systems: Concurrent and Distributed Software Design

4.17. Thread package architectures

We have studied, in general terms, how processes and threads are supported by operating systems and language runtime systems. We now look at some specific thread packages. We have established that an operating system may support only one process per address space (Figure 4.17(b)) or it may support many (Figure 4.17(c)). In the latter case we have assumed implicitly that every user thread will be registered as a kernel thread. We now describe and evaluate various alternative approaches. The discussion is based on Pham and Garg (1996).

User threads without kernel threads (Figure 4.17(b))

Thread switching at user level is fast since it does not involve a call into the operating system. Since each application may ...