UGC-NET | UGC-NET CS 2017 Nov – III | Question 51
User level threads are threads that are visible to the programmer and are unknown to the kernel. The operating system kernel supports and manages kernel level threads. Three different types of models relate user and kernel level threads. Which of the following statements is/are true ? (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
(A)
(a) is true; (b) is false
(B)
(a) is false; (b) is true
(C)
Both (a) and (b) are true
(D)
Both (a) and (b) are false
Answer: (A)
Explanation:
(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
So statement a is true and statement b is false as in many to many , we map kernel threads and not user threads.
So, option (A) is correct.
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Last Updated :
21 Mar, 2018
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