What is CPU cache and what is it used for? We discuss that in this post. A central processing unit (CPU) is also known as a central processor. Alternatively, people refer to it as the main processor or just the processor. The CPU is the electronic circuitry that executes instructions comprising a computer program. The CPU performs:
a) Basic arithmetic,
b) Logic,
c) Controlling,
d) and lastly; input/output (I/O) operations specified by the instructions in the program.
This differs with external components such as main memory and I/O circuitry, and specialized processors such as graphics processing units (GPUs).
Read: The Difference Between Desktop and Mobile CPUs
What is CPU cache
A CPU cache is a hardware cache used by the central processing unit (CPU) of a computer to reduce the average cost (time or energy) to access data from the main memory. A cache is a smaller, faster memory, located closer to a processor core. It stores copies of the data from frequently used main memory locations. Most CPUs have a hierarchy of multiple cache levels (L1, L2, often L3, and rarely even L4), with different instruction-specific and data-specific caches at level 1.
What is CPU cache used for?
When the processor needs to read from or write to a location in the main memory, it first checks whether a copy of that data is in the cache. If so, the processor immediately reads from or writes to the cache, which is much faster than reading from or writing to the main memory.
Most modern desktop and server CPUs have at least three independent caches: an instruction cache to speed up executable instruction fetch, a data cache to speed up data fetch and store, and a translation lookaside buffer (TLB) used to speed up virtual-to-physical address translation for both executable instructions and data. The data cache is usually organized as a hierarchy of more cache levels (L1, L2, etc).
Working memory is the actual data used by your application (as well as a copy of the executable itself; which in the old days you were freely able to modify at runtime). This is the only thing you really need to worry about as a computer user. It is stored in the main memory which is (almost always) a different physical object in your computer.
The caches here are all on your CPU (which is why they are faster for your CPU to access than your RAM modules; which is where it has to look if it can’t find what it needs in the cache).