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Saving Master Data on Cache-To-Cache Transfer

IP.com Disclosure Number: IPCOM000061817D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brey, TM: AUTHOR [+6]

Abstract

In a store in cache system, the valid copy of the data sometimes resides in the cache of one of the processors of the system instead of in main memory. If there is a request for the data from another processor or a channel of the system, the valid copy is transferred directly from the cache containing the valid data to the cache of the requesting element of the system. Sometimes a valid copy cannot be transferred "cache-to-cache". Then, the interrogating element goes to the directory of the cache containing the valid data to determine if the data has been changed while it was in that cache. If the data has not been changed, the requestor goes to main memory to obtain a copy of the data which, since it has not been changed, is also valid.

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Saving Master Data on Cache-To-Cache Transfer

In a store in cache system, the valid copy of the data sometimes resides in the cache of one of the processors of the system instead of in main memory. If there is a request for the data from another processor or a channel of the system, the valid copy is transferred directly from the cache containing the valid data to the cache of the requesting element of the system. Sometimes a valid copy cannot be transferred "cache-to-cache". Then, the interrogating element goes to the directory of the cache containing the valid data to determine if the data has been changed while it was in that cache. If the data has not been changed, the requestor goes to main memory to obtain a copy of the data which, since it has not been changed, is also valid. If the data has been changed, then valid data has been lost and the system has to be stopped.

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