This is for Operating Systems Concepts... Evaluate the performance of the follow

Question

This is for Operating Systems Concepts...

Evaluate the performance of the following solution using locks for 100 threads. Situation: How long does it take to a thread that was already inside of the critical-section and was temporary removed from the CPU to be re-scheduled again in the CPU? Assume round-robin scheduling, and time slide of 5 millisecond int TostAndSet (int -old ptr, int new) nt old -.old ptzs 1/ Eetch old value old ptr-new return old; at old ptr // store 'new into old ptr // return the old value 1typedef struct lock t int flag; void init(lock t lock) 770 indicates that lock is available, 1 that it is held lock->flag-0 void lock (lock t lock) while (TestAndset (&lock-;>flag, 11) ;1 spin-wait (do nothing) 12 13 14 15 void unlock (lock t lock) 16 17 lock->flag 0 a) Using 1 CPU b) Using 100 CPUs

Explanation / Answer

a. using single CPU, the round robin scheduling will take the time is number of threads * time slot,
i.e in the above example 99 * 5 ms (1 thread already waiting state and remaining 99 are in queue )
b. using multiple CPU, if 100 CPUs are there and consider each having 1 core, so 100 CPUs and 100 cores, will execute each thread so, it will take only 5 ms to get the next time slot

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