UPPCL 2018 AE closed

Question

consider the following code

int count=0;

void *thfunc()

{

      int ctr=0;

      for ( ctr=0 ; ctr<100 ; ctr++ )

                  count++ ;

}

 

if thfunc is executed by two threads concurrently in a uniprocessor system ,what will be the MINIMUM  value of count when both threads complete their execution ? Assume the count++ is performed using three instructions : (i) read value of count from memory to a cpu register R , (ii) increment R , (iii)  store the value of R in memory.

 

A. 200

B. NONE OF ABOVE

​​​​​​​C. 100

​​​​​​​D. 2

Comments

@Deepanshu

in that question count value is initialized with 1 but here count value is initialized with 0.

I think it could take minimum value 1.

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Think about the case when one thread is executing 1 time and other thread is executing 99 times. Now suppose both read count as 0 and other thread executed 99 times and updated count to 99, now thread one which have already read count as 0 will increment it by 1 and write in memory.

so minimum value would be 1.

None of these should be the answer

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@Shaik Masthan  

can you please check this question?