Changes

= Location of the problem - Local cache =

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The caching coherency protocol would not allow other party to access the data. Except those data shares a cache block with data. Those data are protected by a hardware write lock that only one core can hold at a time. When two processors are both altered data, the protocol would force the first participant to update the whole unit despite a lack of logical necessity. Each update of an individual element of a cache line marks the line as invalid. Other processors accessing a different element in the same line see the line marked as invalid. They are forced to fetch a more recent copy of the line from memory or elsewhere, even though the element accessed has not been modified. This is because cache coherency is maintained on a cache-line basis, and not for individual elements. As a result, there will be an increase in interconnect traffic and overhead.