Cache
Cache is a small, high-speed memory located inside or very close to the CPU that stores frequently used data and instructions.
It helps the processor access information faster than from RAM.
Why cache exists
The CPU is extremely fast. RAM is slower than the CPU. If the CPU had to wait for RAM every time, performance would drop.
Cache solves this problem by storing commonly used data closer to the processor.
How it works
- The CPU requests data.
- It first checks the cache.
- If data is found — this is called a cache hit.
- If not found — this is called a cache miss, and the CPU retrieves data from RAM.
Cache reduces the need to access slower memory.
Levels of Cache
Modern CPUs use multiple cache levels:
L1 Cache
- Smallest
- Fastest
- Located inside each CPU core
L2 Cache
- Larger than L1
- Slightly slower
- Usually dedicated per core
L3 Cache
- Larger
- Shared between cores
- Slower than L1 and L2 but faster than RAM
Some high-end processors may also include L4 cache.
Cache Size
Cache is measured in:
- Kilobytes (KB)
- Megabytes (MB)
More cache can improve performance, especially in repetitive tasks.
Cache vs RAM
- Cache = smaller, much faster, inside/near CPU
- RAM = larger, slower, main system memory
Cache acts as a buffer between CPU and RAM.
Why it is important
- Reduces memory access time
- Improves CPU efficiency
- Speeds up repetitive operations
- Enhances overall system performance
Without cache, the CPU would constantly wait for data from RAM.
A simple example
Think of cache as a notepad next to your desk. Instead of walking to a cabinet (RAM) every time, you keep frequently used information on the notepad.
Related terms
- What is CPU?
- What is RAM?
- What is Core?
Source
Information simplified from the Wikipedia article “CPU cache”.