What is Cache Memory?? Explained in Detail...

# Cache Memory???

Cache memory, also called CPU memory, is random access memory (RAM) that a computer microprocessor can access more quickly than it can access regular RAM. Thismemory is typically integrated directly with the CPU chip or placed on a separate chipthat has a separate bus interconnect with the CPU. 

The basic purpose of cache memory is to storeprogram instructions that are frequently re-referenced by software during operation. Fastaccess to these instructions increases the overall speed of the software program. As the microprocessor processes data, it looks first in the cache memory; if it finds the instructions there (from a previous reading of data), it does not have to do a more time-consuming reading of data from larger memory or other data storage devices.

Most programs use very few resources once they have been opened and operated for a time, mainly because frequently re-referenced instructions tend to be cached. This explains why measurements of system performance in computers with slower processorsbut larger caches tend to be faster than measurements of system performance in computers with faster processors but more limited cache space. Multi-tier or multilevel caching has become popular in server and desktop architectures, with different levels providing greater efficiency through managed tiering. Simply put, the less frequently access is made to certain data or instructions, the lower down the cache level the data or instructions are written.

# Cache memory levels explained

Cache memory is fast and expensive. Traditionally, it is categorized as "levels" that describe its closeness and accessibility to the microprocessor:

• Level 1 (L1) cache is extremely fast but relatively small, and is usually embedded in the processor chip (CPU).
• Level 2 (L2) cache is often more capacious than L1; it may be located on the CPU or on a separate chip or coprocessor with a high-speed alternative system bus interconnecting the cache to the CPU, so as not to be slowed by traffic on the main system bus.
• Level 3 (L3) cache is typically specialized memory that works to improve the performance of L1 and L2. It can be significantly slower than L1 or L2, but is usually double the speed of RAM. In the case of multicore processors, each core may have its own dedicated L1 and L2 cache, but share a common L3 cache. When an instruction is referenced in the L3 cache, it is typically elevated to a higher tier cache.

#Ankit Goyal#