Cache Operation :

• Read hits
  – This is what we want!
  • Read misses
  – Stall the CPU, fetch block from memory, write to cache
  (replace), restart CPU
  • Write hits:
  – Two policies to keep consistency: 1) Write-through: replace data in all levels cache and memory2)Write-back: write the data only into the cache. The
  modified data is written to the lower level when replaced
  • Write misses:
  – Read the entire block into the cache, then write the word