Write Policies

 

Write-Through

• Data is written to the block in the cache and the block in the lower-level memory
• Cycle time is that of memory
• Memory is always coherent

Write-Back

• Data is only written to the cache
• Modified blocks are written to memory only when replaced
• Cycle time of a hit is that of the cache
• Uses dirty bits to mark blocks which need to be written back when replaced

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