Snooping Protocol

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What Does Snooping Protocol Mean?

Snooping protocol ensures memory cache coherency in symmetric multiprocessing (SMP) systems. Each processor cache on a bus monitors, or snoops, the bus to verify whether it has a copy of a requested data block. Before a processor writes data, other processor cache copies must be invalidated or updated.

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Snooping protocol is also known as bus-snooping protocol.

Techopedia Explains Snooping Protocol

The two snooping protocol types are:

Write-Invalidate: Before changing its copy, a data-writing processor invalidates copies of data in all other system processor caches. This action is communicated by an invalidation signal sent over the bus.
Write-Update: A data-writing processor announces new data through the bus. All affected caches are updated with the new data.

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Margaret Rouse
Senior Editor
Margaret Rouse
Senior Editor

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.