The read access times and the hit ratios for different caches in a memory hierarchy are as given below. Read access time Cache Hit ratio (in nanoseconds) 1-cache 0.8 D-cache 2. 0.9 L2-cache 0.9 The read access time of main memory is 90 nanoseconds. Assume that the caches use the referred-word-first read policy and the write back policy. Assume that all the caches are direct mapped caches. Assume that the dirty bit is always 0 for all the blocks in the

The read access times and the hit ratios for different caches in a memory hierarchy are as given below. Read access time Cache Hit ratio (in nanoseconds) 1-cache 0.8 D-cache 2. 0.9 L2-cache 0.9 The read access time of main memory is 90 nanoseconds. Assume that the caches use the referred-word-first read policy and the write back policy. Assume that all the caches are direct mapped caches. Assume that the dirty bit is always 0 for all the blocks in the

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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The memory access time is I nanosecond for read operation with a hit in cache. * nanoseconds for a read operation with a miss in cache, 2 nanoseconds for a write operation with a hit in cache and 10 anoseconds for a write operation with a miss in cache. Execution of a sequence of instructions involves 100 instruction fetch operations, 60 memory operand read operations and 40 memory operand write operations. The cache hit-ratio is 0.9. The average memory access time (in nanoseconds) in executing the sequence of instructions is
. Cache Write Policies In a cache system using a write-back policy, if a cache block is modified and marked as "dirty" but not yet updated in the main memory, and that block is selected for replacement, what action should be taken to ensure data integrity?
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Question 23 Some portion of cache system A represented below. The system is byte-addressable and the block size is one word (4 bytes). The tag and line number are represented with a binary numbers. The contents of words in the block are represented with hexadecimal. Tag 10 1000 0100 1001 10 1000 0100 1001 10 1000 0100 1001 10 1000 0100 1101 Line Number 0110 1101 0110 1110 0110 1111 B1 FF B8 A1 FF B8 B1 FF B8 A1 FF B8 B1 FF B8 0111 0000 1. What is the size of the main memory of this system? 2. What is the size of the cache memory of this system? 00 Word within block 2016 6116 C116 2116 01 10 11 3216 7216 C216 D216 4216 8216 4116 A216 E216 9216 5216 B216 3. If the CPU requests to read memory address A1 25 BA, what data does the CPU receive? 4. If the CPU requests to read memory address A1 35 C2, what data does the CPU receive? 5. If we access memory in the following order in cache system A: A1 FF B8 how many cache misses would occur for the data request?
Cache Mapping a. A computer system has a main memory with 128 blocks and a cache with 32 blocks. If it uses direct mapping, how many main memory blocks can be mapped to a single cache block? b. In a set-associative cache with 64 blocks and divided into 4 sets, determine the associativity of each set. c. For a fully associative cache with 256 blocks, how many sets are there?
Consider a cache with 128 blocks. The block size is 32 bytes. Find the number of tag bits, index bits, and offset bits in a 32-bit address if you design it as a) Direct-mapped b) 8-way Set Associative
5. A computer has an L1 and L2 cache, backed up by DRAM which is backed up by virtual memory. The TLB and L1 caches have hit times of .5 ns. The TLB's backup is the page table in DRAM while L1 cache's backup is an L2 cache. The L2 cache has a hit time of 1.5 ns. DRAM has a hit time of 10 ns. Swap space has a hit time of 2,500,000 ns. The hit rates are: TLB: 98.8%, L1: 91.5%, L2: 97.7%, DRAM: 99.9998% and swap space 100%. What is the effective access time?
Q: A set-associative cache has a block size of 256 bytes and a set size of 2. The cache can accommodate 32 KB. . The size of main memory is 256 KB. Design the cache structure and show how the processor’s addresses are interpreted. Note: this question is related from coal subject.
Consider a 2-block fully associative cache. The following blocks from main memory are accessed which need to be mapped to cache: P, Q, P, R. Which block is replaced from the cache when the last block (block R) is accessed? Assume FIFO replacement policy.
This chapter explains how to implement the four cache replacement policies.
7. Show the final data and tags of the direct-mapped cache shown below for the given memory contents and data access sequence. As shown, you have 8-bit addresses and 4 bytes of data in each block. You can assume write-through and write-allocate write strategies on write hits and misses respectively. Data Access Sequence Address Data 00 01 11 00 00 10 10 00 00 10 01 00 00 01 00 00 00 11 01 00 00 10 10 00 00 01 11 00 00 10 01 00 00 10 00 00 00 10 10 00 Op. lw lw SW lw SW lw lw SW lw lw hits = misses = 32 642 124 I 00 01 10 11 Direct-Mapped Cache V Tag Data hit rate = miss rate = Memory Address 00 00 10 00 00 00 11 00 00 01 00 00 00 01 01 00 00 01 10 00 00 01 11 00 00 10 00 00 00 10 01 00 00 10 10 00 00 10 11 00 00 11 00 00 00 11 01 00 Data 435 9 47 13 7586 86 43 48 673 4 972 1003