Terminology » Components » L1, L2, and L3 Cache Memory: Understanding the Differences

L1, L2, and L3 Cache Memory: Understanding the Differences

cache memory l1 cache l2 cache l3 cache cpu performance

This article compares the different levels of cache memory: L1, L2, and L3. It will explain what they are and the key differences between them.

What is Cache?

In computing, cache is a type of high-speed memory designed to reduce the average time it takes to access data from main memory (RAM). It stores frequently used instructions or data, allowing the CPU to access them more quickly.

There are several types of cache, including:

  • L1/L2/L3 cache: These are the main types we’ll be discussing.
  • RAM cache: In essence, this is the same as CPU cache. L1/L2 caches data from RAM, while RAM caches data from the hard disk. For example, when Windows loads, it loads several required libraries into RAM.
  • Disk cache: Similar to RAM cache, disk cache holds recently read or written data from a hard drive (HD). This speeds up subsequent reads of that data. Most modern hard drives have around 8 MB of cache memory.
  • Software cache: Software often needs to cache data into RAM that it uses frequently. This data is often processed data from a file, translated by the program into another data structure. Examples include web browsers like Internet Explorer and games.

Cache memories are located closer to the CPU than RAM, and store recently accessed data from RAM. They hold instructions that are to be executed next and variables needed by the CPU.

difference between L1 L2 L3 Cache memory

Level 1 cache is stored on the CPU itself, while L2 and L3 caches are stored near, but not directly on, the CPU. L1/L2/L3 cache is generally more expensive than RAM.

L1 Cache Memory

  • Location: On-chip (integrated directly into the CPU)
  • Access Time: 2 to 8 nanoseconds (ns)
  • Typical Sizes: 8 KB, 64 KB, 128 KB
  • Technology: SRAM (Static RAM)
  • Management: Hardware

L2 Cache Memory

  • Location: Off-chip (located near the CPU, but not directly on it)
  • Access Time: 3 to 10 ns
  • Typical Sizes: 256 KB, 1 MB, 2 MB
  • Technology: SRAM
  • Management: Hardware

L3 Cache Memory

  • Location: Off-chip
  • Access Time: 10 to 20 ns
  • Typical Sizes: 4 to 8 MB (laptop), 8 to 32 MB (desktop)

L1 vs L2 vs L3 Cache: Key Differences

The following table summarizes the differences between L1, L2, and L3 cache memory:

FeaturesL1 CacheL2 CacheL3 Cache
LocationDirectly built into the processor; stores CPU’s recently accessed information.Located outside and separated from the CPU chip core.Built on the motherboard within the CPU module; used by all cores.
SizeSmallest cacheLarger than L1 and smaller than L3Largest cache
Cache type/NameLevel 1, primary, or internal cacheLevel 2, secondary, or external cacheLevel 3 or external cache
SpeedFastest cacheSlower than L1 but faster than L3Slowest cache
UseEach core in the CPU has its own L1 cache memoryEach core in the CPU has its own L2 cache memoryAll cores in the CPU share the same L3 cache memory