Write-once (cache Coherence)

Write-once (cache Coherence)

In cache coherency protocol literature, Write-Once was the first write-invalidate protocol defined. It has the optimization of executing write-update on the first write and a write-invalidate on all subsequent writes, reducing the overall bus traffic in consecutive writes to the computer memory. It was first described by James R. Goodman in (1983). Cache coherence protocols are an important issue in Symmetric multiprocessing systems, where each CPU maintains a cache of the memory.