User level threads are threads that are visible to the programmer and ...
(a) (i) The Many - to - one model maps many user threads to one kernel thread (ii) The one - to - one model maps one user thread to one kernel thread (iii) The many - to - many model maps many user threads to smaller or equal kernel threads
(b) (i) Many - to - one model maps many kernel threads to one user thread (ii) One - to - one model maps one kernel thread to one user thread (iii) Many - to - many model maps many kernel threads to smaller or equal user threads All satement are correct. So, option (A) is correct.
View all questions of this test
User level threads are threads that are visible to the programmer and ...
(a) (i) The Many - to - one model maps many user threads to one kernel thread (ii) The one - to - one model maps one user thread to one kernel thread (iii) The many - to - many model maps many user threads to smaller or equal kernel threads
(b) (i) Many - to - one model maps many kernel threads to one user thread (ii) One - to - one model maps one kernel thread to one user thread (iii) Many - to - many model maps many kernel threads to smaller or equal user threads All satement are correct. So, option (A) is correct.
User level threads are threads that are visible to the programmer and ...
Explanation:
User-level threads and kernel-level threads are two different types of threads used in operating systems. The operating system kernel supports and manages kernel-level threads, while user-level threads are managed by the programmer.
User-Level Threads:
- User-level threads are threads that are visible to the programmer and are unknown to the kernel.
- These threads are created and managed by the application or programming language without any intervention from the operating system.
- User-level threads are lightweight and have low overhead since they do not require kernel involvement for thread management.
- However, user-level threads are limited by the fact that if one thread blocks or performs a system call, all other threads in the process are also blocked.
Kernel-Level Threads:
- Kernel-level threads are threads that are managed and supported by the operating system kernel.
- The kernel provides system calls and services for creating, scheduling, and managing kernel-level threads.
- Kernel-level threads have the advantage of being able to run in parallel on multiple processors or cores.
- However, they have higher overhead compared to user-level threads due to the involvement of the kernel in thread management.
Models of User and Kernel Level Threads:
There are three different models that relate user-level threads to kernel-level threads:
1. Many-to-One Model:
- In this model, many user threads are mapped to a single kernel thread.
- All user-level threads of a process share the same kernel-level thread.
- This model has low overhead and is easy to implement but lacks the ability to run threads in parallel on multiple processors or cores.
2. One-to-One Model:
- In this model, each user thread is mapped to a separate kernel thread.
- Each user-level thread has a corresponding kernel-level thread.
- This model allows threads to run in parallel on multiple processors or cores, but it has higher overhead compared to the many-to-one model.
3. Many-to-Many Model:
- In this model, many user threads are mapped to smaller or equal kernel threads.
- The mapping between user and kernel threads can be dynamic and change over time.
- This model provides a balance between the flexibility of the one-to-one model and the efficiency of the many-to-one model.
Correct Answer:
The correct answer is option (a) - (a) is true; (b) is false.
- The many-to-one model maps many user threads to one kernel thread.
- The one-to-one model maps one user thread to one kernel thread.
- The many-to-many model maps many user threads to smaller or equal kernel threads.