What might be a benefit of splitting up the L1 cache into separate instruction and data caches?

The most important advantage of splitting the cache memory is the increase in bandwidth that results. Also the Instruction cache does not need to manage a processor store. Having it separate from the Data cache makes possible to simplify its design. Re- placement policy may also result more effective.

How does split cache work?

A split cache is a cache that consists of two physically separate parts, where one part, called the instruction cache, is dedicated for holding instructions and the other, called the data cache, is dedicated for holding data (i.e., instruction memory operands).

How does Harvard architecture work?

The Harvard architecture stores machine instructions and data in separate memory units that are connected by different busses. In this case, there are at least two memory address spaces to work with, so there is a memory register for machine instructions and another memory register for data.

What is instruction memory and data memory?

Instruction memory is the memory that instructions are fetched from, and data memory is the memory where the data is written to and read from.

How does L1 cache work?

L1 (Level 1) cache is the fastest memory that is present in a computer system. In terms of priority of access, the L1 cache has the data the CPU is most likely to need while completing a certain task. The L1 cache is usually split into two sections: the instruction cache and the data cache.

Why are L1 caches split?

Most of the reason for split L1 is to distribute the necessary read/write ports (and thus bandwidth) across two caches, and to place them physically close to data load/store vs. instruction-fetch parts of the pipeline. Also for L1d to handle byte load/store (and on some ISAs, unaligned wider loads/stores).

What is L1 cache and L2 cache?

L1 is “level-1” cache memory, usually built onto the microprocessor chip itself. L2 (that is, level-2) cache memory is on a separate chip (possibly on an expansion card) that can be accessed more quickly than the larger “main” memory. A popular L2 cache memory size is 1,024 kilobytes (one megabyte).

Why we need modified Harvard architecture?

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Do modern CPUs have a split-cache architecture?

Most of the modern CPUs do have separate instruction cache and data cache (usually the difference exists only at L1, and is gone at L2 and above). [WikiModifiedHarvard] states that having split-cache is enough to name the architecture “Modified Harvard”.

What is a modified Harvard architecture?

In [WikiModifiedHarvard], “Modified Harvard” architecture is defined rather vaguely, but it lists three distinct possibilities which are clearly defined as “Modified Harvard”. These architectures which are clearly defined as “Modified Harvard”, are: Split Cache, Access Instruction Memory as Data, and Read Instructions from Data Memory.

What is Harvard architecture in computer architecture?

This means CPU cannot do both things together (read a instruction and read/write data). Harvard Architecture is the computer architecture that contains separate storage and separate buses (signal path) for instruction and data. It was basically developed to overcome the bottleneck of Von Neumann Architecture.

Is it possible to implement JITs in Harvard architecture?

As described in [WikiModifiedHarvard], it is possible to modify pure Harvard architecture to allow executing code from the data address space (which in turn will allow to implement things such as JITs or self-modified code). Still access to constants-which-reside-in-code-segment will be complicated.