Cache Real Estate Management
The Lookup
When a cache miss occurs, a new line must be fetched from memory and placed in the cache. Refer to Figure 17-4 on page 404. Assume that a memory address was submitted to the cache for a lookup and, as shown in the illustration, the Line portion of the address selected set 3 in the directories (i.e., the set of four directory entries at offset 3 in each of the four directories). Assume that all four of the entries are valid, that the cache is a MESI cache (i.e., a WB cache), and that the four entries contain the following:
Entry 3 in Directory 0 contains a Page address of 0349A03h and its 2-bit State field indicates that the line is in the E (Exclusive) state. This means that the cache contains line 3 from ...
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