Multi - threading Models

Many-to-One Model

[ ]Many user-level threads mapped to single kernel thread

* Thread management is done in user space

* Blocking problem

* No support for running in parallel on MP

* Used on systems that do not support kernel threads.

* Green-threads library in Solaris 2

One-to-One Model
[ ]Each user-level thread maps to a kernel thread

* Creating a user thread requires creating the corresponding kernel thread

* Overhead

* Restrict the number of threads supported by the OS

•Examples

* Windows NT/2000

* OS/2

Many-to-Many Model

[ ] Multiplex many user-level threads to a smaller or equal number of kernel threads

[ ] Allows many user level threads to be mapped to many kernel threads.

[ ] Allows OS to create a sufficient number of kernel threads.

•Examples

* Solaris 2, IRIX, HP-UX, Tru64 UNIX

* Windows NT/2000 with the ThreadFiber package