Many-to-One Model

• The many-to-one model (see Fig. 5) maps many user-level threads to one kernel thread.

  Figure 5: Many-to-one model.

  
• Thread management is done by the thread library in user space, so it is efficient; but the entire process will block if a thread makes a blocking system call.
• Also, because only one thread can access the kernel at a time, multiple threads are unable to run in parallel on multiprocessors.