 October 6, 2023
October 6, 2023
October 6, 2023
###### Programming-for-Output-Problems
October 6, 2023
 Question 1
A hierarchical memory system that uses cache memory has cache access time of 50 nano seconds, main memory access time of 300 nanoseconds, 75% of memory requests are for read, hit ratio of 0.8 for read access and the write-through scheme is used. What will be the average access time of the system both for read and write requests ?
 A 157.5 n.sec. B 110 n.sec. C 75 n.sec D 82.5 n.sec.
Question 1 Explanation:
Avg. time to read the data = 0.8(50) + 0.2(300+50) = 40 + 70 = 110 ns
Avg. memory access time = (Seq. of data read request * time to read data) + (freq. Of data write request * time to write the data)
= (0.75 × 110) + (0.25 × 300)
⤿Since write through is mentioned in question. So write operation will take place in memory and not in cache.
= 82.5 + 75.0
= 157.5 ns
Question 1 Explanation:
Avg. time to read the data = 0.8(50) + 0.2(300+50) = 40 + 70 = 110 ns
Avg. memory access time = (Seq. of data read request * time to read data) + (freq. Of data write request * time to write the data)
= (0.75 × 110) + (0.25 × 300)
⤿Since write through is mentioned in question. So write operation will take place in memory and not in cache.
= 82.5 + 75.0
= 157.5 ns