3. [21 marks] Consider a computer with a byte-addressable memory. A 40-bit memor

Question

 3. [21 marks] Consider a computer with a byte-addressable memory.  A 40-bit memory address is divided as follows for cache processing.  First, the 8 low-order bits are chopped off to expose the cache-line number. Second, the next 17 low-order bits are inspected to get the cache-container index.  Third, the remaining 15 bits are used as the cache tag.  Hint: What do the direct-mapped and set-associative placement formulas have in common?  a) [7 marks] What is the cache size in bytes?  b) [7 marks] What is the cache-mapping scheme?  c) [7 marks] For a given byte in the cache, how many different bytes in the main memory could possibly be mapped to it? 

Explanation / Answer

3)a) A cache scope might vary rendering to the cache line, he can 32, 64 and 128 bytes.

Cache size influences the presentation of a customer mechanism more straight than perhaps any other cache parameter. The larger the cache, the faster the Cache Manager is probable toward deliver files to users. A small cache can spoil performance because it increases the frequency at which the Cache Manager must discard cached data to make chamber for again requested data

b) cache mapping scheme:It treats the slot as a large array, and the index of the collection is picked after bits of the address (which is why we need the amount of slots to remain a control of 2---otherwise we can't select bits from the address) The arrangement can agonies from many addresses "colliding" in the direction of the same slot, thus causing the cache line to be recurrently evicted, even though there may be empty slots that are not being used, or being used with less frequency. If there is an advantage to the scheme, it is very simple, you don't have to simultaneously match tickets by all slots. You just have one slot to check. If the data is not the slot, it is obvious that this is the slot to get evicted.

c. For a given byte in a cache 2^64 bytes sorts of main reminiscences container be mapped

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