Q1➡| The hit ratio of cache memory is the percentage of access (reads and writes)for which data are found in the cache. Write-through, Write-back are two main policies for memory updation. write-allocation is a policy whereby a cache line is allocated and loaded on a write miss. If it is assumed that write-allocation is always used, which of the following is true.
i ➥ Write-through can only be employed in set-associative memory
ii ➥ The percentage of write operations resulting in a main memory operation will never be larger for Write-back than for Write-through
iii ➥ Write through usually results in a better hit ratio than write-back
iv ➥ Write-back usually results in a better hit ratio than write-through
Q4➡| A page table is maintained partially in cache memory with a hit ratio of 80%. Give the following, what is the Effective Access Time. Cache lookup takes 5 nanosec and memory access time is 100 nanosec.
Q6➡| Cached and interleaved memories are ways of speeding up memory access between CPU’s and slower RAM. Which memory models are best suited (i.e. improves the performance most) for which programs ? (i) Cached memory is best suited for small loops. (ii) Interleaved memory is best suited for small loops (iii) Interleaved memory is best suited for large sequential code. (iv) Cached memory is best suited for large sequential code.
Q8➡| The performance of a file system depends upon the cache hit rate. If it takes 1 msec to satisfy a request from the cache but 10 msec to satisfy a request if a disk read is needed, then the mean time (ms) required for a hit rate ‘h’ is given by :
Q10➡| Consider a system with 2 level cache. Access times of Level 1, Level 2 cache and main memory are 0.5 ns, 5 ns and 100 ns respectively. The hit rates of Level 1 and Level 2 caches are 0.7 and 0.8 respectively. What is the average access time of the system ignoring the search time within cache?
Q12➡| Consider a system with 2 level cache. Access times of Level 1 cache, Level 2 cache and main memory are 1 ns, 10 ns, and 500 ns, respectively. The hit rates of Level 1 and Level 2 caches are 0.8 and 0.9, respectively. What is the average access time of the system ignoring the search time within the cache?
Q13➡| A dynamic RAM has a memory cycle time of 64 nsec. It has to be refreshed 100 times per msec and each refresh takes 100 nsec. What percentage of the memory cycle time is used for refreshing?
