user thread

To make threads cheap and fast, they need to be implemented at user level
◆ Kernel-level threads are managed by the OS
◆ User-level threads are managed entirely by the run-time system (user-level library)z
User-level threads are small and fast
◆ A thread is simply represented by a PC, registers, stack, and small thread control block (TCB)◆ Creating a new thread, switching between threads, and synchronizing threads are done via procedure call
» No kernel involvement
◆ User-level thread operations 100x faster than kernel threads