One-to-One Model

• The one-to-one model (see Fig. 4.6) maps each user thread to a kernel thread.

  Figure 4.6: One-to-one model.

  
• It provides more concurrency than the many-to-one model by allowing another thread to run when a thread makes a blocking system call;
• it also allows multiple threads to run in parallel on multiprocessors.
• The only drawback to this model is that creating a user thread requires creating the corresponding kernel thread.
• Because the overhead of creating kernel threads can burden the performance of an application, most implementations of this model restrict the number of threads supported by the system.
• Linux, along with the family of Windows OSs implement the one-to-one model.