What is associative mapping in computer architecture?
Associative Mapping – This means that the word id bits are used to identify which word in the block is needed, but the tag becomes all of the remaining bits. This enables the placement of any word at any place in the cache memory.
What is associative mapping in cache explain how it is different from set associative mapping?
Difference between Direct-mapping, Associative Mapping & Set-Associative Mapping
| Associative Mapping | Set-Associative Mapping | |
|---|---|---|
| 5. | Search time is more as the cache control logic examines every block’s tag for a match. | Search time increases with number of blocks per set. |
What are the disadvantages of direct and associative cache memory mapping techniques?
Disadvantage of direct mapping: 1. Each block of main memory maps to a fixed location in the cache; therefore, if two different blocks map to the same location in cache and they are continually referenced, the two blocks will be continually swapped in and out (known as thrashing).
What is set associative cache?
Set Associative Cache • Set associative caches are a. compromise between fully associative caches and direct-mapped caches. In a set associative cache, there are a fixed number of locations (called a set) that a given address may be stored in. The number of locations in each set is the associative of the cache.
What is the difference between associative cache memory and content addressable memory?
The cache needs to be much faster than main memory. This approach is more economical than the use of fast memory devices to implement the entire main memory….Differences between associative and cache memory :
| S.No. | Associative Memory | Cache Memory |
|---|---|---|
| 1 | A memory unit access by content is called associative memory. | A fast and small memory is called cache memory. |
Why is set associative mapping technique more advantageous than direct or associative mapping technique?
Advantages of Set-Associative mapping Set-Associative cache memory has highest hit-ratio compared two previous two cache memory discussed above. Thus its performance is considerably better.
Why replacement algorithm is used in set associative mapping?
In the associative mapping, any block of main memory can go to any block of cache, so it has got the complete flexibility and we have to use proper replacement policy to replace a block from cache if the currently accessed block of main memory is not present in cache.
How is associative mapping used in a computer?
The whole arrangement of Associative Mapping Technique is shown in the figure below. This mapping technique is intermediate to the previous two techniques. Blocks of the cache are grouped into sets, and the mapping allows a block of main memory to reside in any block of a specific set.
How many blocks are used in associative mapping?
The TAG field of associative mapping technique is divided into two groups, one is termed as SET bit and the second one is termed as TAG bit. Each set contains 4 blocks, total number of set is 32. The main memory address is grouped into three parts: low-order 5 bits are used to identifies a word within a block.
How are cache lines grouped in set associative mapping?
SET-ASSOCIATIVE MAPPING • Set-associative mapping is a combination of direct and associative mapping • The cache lines are grouped into sets • The number of lines in a set can vary from 2 to 16 • The data can be stored in any of the lines in the set 6.
Which is better set associative or direct mapping?
The performance of direct mapping cache is not good as requires replacement for data-tag value. In Set-Associative cache memory two or more words can be stored under the same index address. Here every data word is stored along with its tag. The number of tag-data words under an index is said to form a text.