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Write-back Cache

A cache writing strategy where data is only written to the cache initially, and main memory is updated only when the cache line is evicted.

Categoryhardware

Overview

Write-back (also called write-behind) is the most common strategy in high-performance CPUs. Updates are made only to the cache, and the cache line is marked as 'dirty.' The data is written to main memory only when that line needs to be replaced by new data.

Advantages

  • High Performance: Write operations happen at cache speed.
  • Reduced Bus Traffic: Multiple writes to the same location only result in one write to main memory.

Disadvantages

  • Complexity: Requires tracking 'dirty' bits and ensuring cache coherency in multi-core systems.

Related Terms

Write-through Cache