Elements of Cache Design Quiz for Computer Architecture

12 Questions

What is the primary goal of cache design in computer architecture?

To improve the speed of memory access

What is the trade-off when increasing the cache size?

Slower access times and more data storage

How is cache memory organized?

Into lines or blocks

What is the purpose of a replacement policy in cache design?

To evict an existing item to make room for a new one

What is the characteristic of a fully associative cache?

Each block of main memory can map to any cache line

What is the benefit of loading an entire cache line when the processor requests data?

It increases the likelihood of future data requests being satisfied

What is the primary purpose of a write buffer in a cache system?

To temporarily store write operations before they are written to the main memory

What is the main advantage of a larger block size in a cache system?

It reduces the number of memory accesses

What is the main purpose of prefetching in a cache system?

To predict what data the processor will need next

What is the characteristic of a multi-level cache hierarchy?

Each level has different characteristics in terms of size, speed, and proximity to the CPU

What is the main difference between Write-Through and Write-Back policies?

Write-Through writes data to both the cache and main memory simultaneously

What is the purpose of cache replacement policies?

To determine which data to replace in the cache when it is full

Study Notes

Cache Design Elements

Cache design aims to improve memory access speed by storing frequently accessed data closer to the processor.
Effective cache design involves balancing cache size and access time.

Cache Size

Cache size is a critical factor, as larger caches can store more data but may have longer access times.
A balance between size and speed is essential.

Cache Lines

Cache memory is divided into lines or blocks, each storing a fixed amount of data.
When the processor requests data, an entire line is loaded into the cache, increasing the likelihood of future data requests being satisfied from the cache.

Associativity

Associativity refers to how the cache is organized in terms of mapping data from main memory.
There are three types of associativity:
- Direct-Mapped Cache: Each block of main memory maps to exactly one cache line.
- Set-Associative Cache: Each block of main memory can map to a set of cache lines.
- Fully Associative Cache: Each block of main memory can map to any cache line.

Replacement Policy

When a cache is full, a replacement policy determines which existing item should be evicted to make room for the new one.
Common replacement policies include Least Recently Used (LRU), First-In-First-Out (FIFO), and random replacement.

Write Policy

Write policy determines how writes to the cache are handled.
There are two types of write policies:
- Write-Through: Data is written to both the cache and main memory simultaneously.
- Write-Back: Data is written to the cache first, and then to main memory at a later time.

Block Size

Block size is the size of the data block transferred between main memory and cache.
A larger block size can reduce the number of memory accesses but may result in more data being loaded into the cache.

Cache Hierarchy

Modern systems often have multiple levels of cache (L1, L2, and sometimes L3).
Each level has different characteristics in terms of size, speed, and proximity to the CPU.
Efficient coordination between these levels is vital for overall system performance.

Write Buffer and Prefetching

A write buffer may be used to temporarily store write operations before they are written to the main memory.
Prefetching involves predicting what data the processor will need next and loading it into the cache before it is actually requested.
This can help reduce latency.

Computer Architecture: Elements of Cache Design Quiz