1. If the base CPI with a perfect memory system is 1.5, what is the CPI for thes

Question

1. If the base CPI with a perfect memory system is 1.5, what is the CPI for these cache organizations: (A) 16KB direct-mapped unified cache using write back (miss rate = 0.029) (B) 16KB two-way set-associative unified cache using write back (miss rate = 0.022) (C) 32KB direct-mapped unified cache using write back (miss rate = 0.020) Assume the memory latency is 40 clock cycles, the transfer rate is four bytes per cycle, and that 50% of the transfers are dirty. There are 32 bytes per block and 20% of the instructions are data transfer instructions (loads or stores). There is no write buffer and the cache uses write allocate on a cache miss.

Explanation / Answer

1)
16KB direct-mapped unified cache using write back.

CPI = CPIbase + Stalls cycles/instruction

= 1.5 + [Miss rate x miss penalty x memory access/instruction x no of blocks]

= 1.5 + [0.029 x (40 + 32/4) x 1.2 x 1.5]

= 4.0056

2)
CPI = 1.5 + [0.022 x 48 x 1.2 x 1.5]

=3.4008

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.