Changes between Version 7 and Version 8 of CacheCoherence


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Timestamp:
Jul 12, 2009, 12:51:05 PM (15 years ago)
Author:
alain
Comment:

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  • CacheCoherence

    v7 v8  
    1717
    1818The TSAR architecture wants to guaranty the cache coherence by hardware, for both the data and instruction L1 caches. Reflecting the different behaviour of data & instruction caches, the "hybrid" cache coherence protocol defines two different strategies, depending on the number of copies :
    19  * '''MULTICAST_UPDATE''' :  the modifications of shared data are very frequent events, but the number of copies is generally not very high. When the number of copies is smaller than the DHCCP threshold, the cache controller registers the locations of all the copies, and send a ''multicast_update'' transaction
    20 to the concerned L1 caches.
    21  * '''BROADCAST_INVAL''' : the modifications of shared code rare events ( self modifying code, or dynamic libraries ), but the number of replicated copies can be very large ( the exception handler, or the libc are generally replicated in all L1 caches ). When the number of copies is larger than the DHCCP threshold, the memory cache controller will simply store the number of copies (without localization) and send a ''broadcast_inval'' transaction  to all L1 caches. 
     19 * '''MULTICAST_UPDATE''' :  the modifications of shared data are very frequent events, but the number of copies is generally not very high. When the number of copies is smaller than the DHCCP threshold, the memory cache controller registers the locations of all the copies, and send a ''multicast_update'' transaction to each concerned L1 cache in case of modification.
     20 * '''BROADCAST_INVAL''' : the modifications of shared code rare events ( self modifying code, or dynamic libraries ), but the number of replicated copies can be very large ( the exception handler, or the libc are generally replicated in all L1 caches ). When the number of copies is larger than the DHCCP threshold, the memory cache controller will simply store the number of copies (without localization) and send a ''broadcast_inval'' transaction  to all L1 caches in case of modication. 
    2221
    2322== 2.  Types of transaction ==