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1 With write caches, a performance increase of writing a data item may be realized upon the first write of the data item by virtue of the data item immediately being stored in the cache's intermediate storage, deferring the transfer of the data item to its residing storage at a later stage or else occurring as a background process.

2 Two writes can become causally related if one write to a variable is dependent on a previous write to any variable if the processor doing the second write has just read the first write.

3 It is the responsibility of the software to include memory barrier instructions after the first write, to ensure that the cache buffer is drained before the second write is executed.

4 Modifications must still create a copy, hence the technique: the copy operation is deferred until the first write.