Question

1. True-false or multiple choice. Provide a one-sentence explanation you will get no credit for a correct answer without a proper explanation. Suggested time to spend on these questions: 10 minutes. [4x5-20ptsl (a) True or false: Peterson's algorithm for mutual exclusion offers bounded wait. b) Thue or falher Cumsider a concumcent program comitingof several 1oad indctioms e instructions (or instructions with similar effects as store). Such a program can never have any race conditions (c) True or false: Solutions based on busy waiing (e.g., mutex/spin locks) are always better than those based on suspending threads/processes that can not proceed past their entry sections (d) Consider a producer-consumer problem with a shared buffer of size 10. Consider a correct solution based on mutex locks. Pick a single answer corresponding to the strongest liveness condition asso- ciated with this program i) depends on the liveness conditions offered by the implementation of the mutex locks, ii) no deadlock,ii) no starvation, (iv) bounded wait.

Answer 1

a. True because using turn variable in Perterson algorithm ensures that there is an order in which process will be allowed to enter into critical section if multiple process are trying to enter critical section. Hence bounded wait is maintained.

b. True as long as there are only load instructions means that shared data will be used for Read purpose only and hence no race condition.

c. False because busy waiting solution unnecessary makes the process wait for the resource and waste the CPU cycle allocated to process. Hence suspending process till the time resource is not available is better alternative .

d. Answer i is correct. It depends on liveness condition offered by implementation in mutex locks because deadlock, starvation and unbounded can happen even in producer consumer problem with any finite size buffer.

Please comment for any clarification.