Cache memory is high-speed memory located in or near the CPU that stores frequently accessed instructions and data to improve performance. It exists in multiple levels, with level 1 cache being the fastest but smallest and embedded in the CPU, level 2 cache being larger but still fast, and level 3 cache being larger still but slower than levels 1 and 2. This multi-level cache hierarchy provides faster access to important data than accessing regular RAM, improving the overall speed of software programs.

1. Multi-Level Cache
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2. Definition of Cache :
• Cache memory is a portion (perhaps several hundred KB) of
high-speed memory located within the CPU itself. In this special
memory area, the machine attempts to keep a copy of that portion of
main memory that is of current interest.
• 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.

3. •The basic purpose of cache memory is to store
program instructions that are frequently re-referenced
by software during operation. Fast access to these
instructions increases the overall speed of the software
program.
•Memory caching is effective because most programs
access the same data or instructions over and over. By
keeping as much of this information as possible in SRAM,
the computer avoids accessing the slower DRAM.

5. Levels of Cache :
• 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.

6. • 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.

7. • Organization of Multilevel Memory System : A CPU should
have rapid, uninterrupted access to its external memories to operate at or near at
its maximum speed. But memories that operate at speed near to that of CPU are
expensive. That’s why different level of memories is used in terms of performance
and costs. Below is the flow-diagram