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What is CPU cache memory? L1, L2 and L3 cache explained

The cache memory of a computer is used to quickly access instructions and data that are used often. The more data and instructions a system can access quickly, the more data it can send to other components of the system, and the faster the system will run. There are three types of cache memory on a computer system: Level 1 (L1), Level 2 (L2), and Level 3 (L3). Each of these levels of cache memory has a different purpose and a different physical location in the computer system.

Most computers have a CPU cache, which is a small amount of RAM located right next to the actual CPU. The purpose of these caches is to store the most commonly used instructions and data. Whenever the CPU needs to access some piece of data, it checks the RAM first. The data in the cache is much closer to the CPU than the data in the main computer memory, and much faster to access, so it’s much faster if the data is in the cache. The CPU cache is divided into smaller sections called levels, which are called L1, L2, and L3 cache. Each level is smaller and faster than the level right above it. The cache is organized into lines, which are typically 64 or 128 bytes

If you’re a technology enthusiast, you’ve probably heard the word cache in several contexts. Whether in web browsers or applications, caching is used everywhere, but what is the relationship between caching and the processor? Can it have a significant impact on the performance of your system?

If you’re wondering these things, you’ve come to the right place, because in this article you’ll find out all about CPU cache and whether it can make your system faster.

Simply put, a cache is a remarkably fast non-volatile memory used to provide data to the CPU. This memory is located on the processor itself and is an essential parameter for the performance of the processor. But what makes the cache so fast?

To answer this question, note that there is a fundamental difference in how cache and RAM are created. Cache memory uses SRAM (static RAM) to store data, while RAM uses DRAM (dynamic RAM).

SRAM cells use transistors to store data, while DRAM uses capacitors and transistors to store data. Because capacitors are used in DRAM cells, they must be replaced frequently because capacitors lose their charge over time. During the refresh cycle, RAM data is not accessible, which slows down RAM operation. SRAM, on the other hand, does not lose charge and is therefore called static RAM.

In addition, the cache memory is located on the processor chip. This allows the processor to access the data faster because it is closer to the CPU. On the other hand, RAM memory is connected to the processor via the motherboard, which makes accessing RAM memory slower.

Given all the advantages of cache memory, you might think that if cache memory is so fast, why not use it instead of RAM. The problem with SRAM is that it is very expensive and takes up a lot of space on the chip compared to RAM. Because of this large size and cost of cache memory, it is divided into three separate blocks, namely L1, L2 and L3 caches.

All these memories have different sizes and operate at different speeds – more on this in the next chapter.

Also read : What is cache-splitting? Does this affect your personal life?

Before understanding how the cache works, it is important to understand why it is needed. The main reason caches are needed is that system memory is not fast enough for the processor.

To clarify: A modern processor runs at 4 GHz in turbo speed. During such a cycle, it can process instructions in a quarter of a nanosecond. In contrast, main memory, which stores data in the system’s cache, takes about 8.8 nanoseconds to send data to the processor.

If you look at the numbers, you’ll see a significant gap between the speed at which the CPU can process data and the speed at which RAM can deliver it to the CPU. To fill this gap, the processor uses a special type of memory called cache memory.

Also read : What is a hard drive defragmenter? Can it speed up your PC?

As mentioned in the previous chapter, caching is fast, but it also has some drawbacks. To overcome these drawbacks, the processor’s cache is divided into three levels.

L1 is the fastest, but smallest of all caches. This cache is also closest to the CPU and delivers the fastest possible data to the CPU. Next is the L2 cache, which is larger but slower than the L1 cache. In multiprocessor processors, the L1 and L2 cache are independent for the processor core, with the L1 cache further divided into a data cache and an instruction cache.

Another cache the processor has, the largest of all, but also the slowest, is the L3 cache. In multiprocessor systems, the L3 cache is shared by the processor cores and, in some cases, placed outside the processor array.

The Intel Core i7-10700K processor has 64 KB of L1 cache per core, 256 KB of L2 cache and 16 MB of L3 cache in total. The size of the L3 cache has increased significantly in recent years, but the L1 cache has only increased by a few KB.

The reason is that when the L1 cache is increased, the processor takes a long time to find the data, which defeats the purpose of the fast cache. Additionally, the fast L1 cache takes up a lot of space on the processor chip, leaving less room available for other components.

To check the cache information in Ubuntu, use the command sudo lshw -C memory

Also read : What is a DNS cache and how does it work?

How does data move through your system?

Now that we have a brief overview of how caching systems are used in modern machines, we can examine how data moves through computers.

The RAM and caches in your system are power-dependent memory systems and therefore cannot hold data after a power outage. Therefore, non-volatile media, such as hard drives, are needed to store system data.

These non-volatile systems use magnetic disks or flash memory to store data and send it to RAM when a program is opened in the system. The CPU then asks RAM to transfer data to the cache; this data contains files and instructions that can be used by the user in the future or that the CPU needs in real time.

The L1 cache contains data that the processor is currently working on; the L2 cache contains files that have recently been used by the processor and may be needed in the future. The L3 cache stores data that can be used by multiple cores to perform tasks.

Also read : What is DNS cache poisoning? How can I protect my computer?

What happens if the data is not in the cache?

We know that data flows from the cache to the CPU and that the cache is important to the CPU. But what happens if the data the processor needs is not in the cache.

When something like this happens, it’s called a cache miss, and the system looks for the data the processor needs and moves it to the cache. There are three types of cache misses that can occur on a system, namely

  • Skip check cache : In this case, there are no instructions in the L1 instruction cache that can be executed by the processor. This lack of cache causes the greatest delay because the CPU cannot perform a task because it does not know which instruction to execute. When such a slip occurs, the system begins to look for the instruction in RAM or main memory.
  • Skip Data : When this cache miss occurs, the processor cannot retrieve the data it should be working with. This happens when there is no data in the L1 data cache. This lack of cache has a moderate effect on system performance because the processor can work with other data until the system gets the information it needs.
  • Skipping data recording : In this case, the data processed by the processor cannot be written to the cache; this can happen if the L1 data cache is full. The lack of a cache results in the least amount of delay, because the data can be stored by the processor in a register and sent to the cache later.

Also read : What is the difference between a GPU and an FPGA?

Cache memory is an integral part of any processor, but how much is needed? As mentioned earlier, the L1 and L2 cache sizes remain the same on most systems. The only cache you need to pay attention to is the L3 cache, and a larger cache will provide better performance.

Some high-end CPU systems can have up to 64 MB of cache, but such cache sizes are too expensive and are used in server applications. If you are an avid gamer and using a multi-core machine, 16 MB of cache is more than enough to meet all your needs.

Also read : How do I get a Google Maps API key?

A technophile driven by curiosity. A bibliophile who loves to travel. An engineering graduate who loves programming and writing about new technologies. I can’t live without coffee.

You can contact Nishai via email: [email protected]

This source has been very much helpful in doing our research. Read more about what is cache memory and let us know what you think.

Frequently Asked Questions

What is L1 and L2 cache memory?

Computer memory is the hardware (ie hard drive, SSD or RAM) used by a computer to store data for use by the CPU. Computer memory is a form of volatile storage, since the data is lost when the power is turned off. There are two main types of computer memory: primary memory and secondary memory. Primary memory is the storage that is part of the same device as the CPU. Secondary memory is storage that is attached to a computer by a cable or wireless interface. Secondary memory is often much larger than primary memory. Remember the last time you got a new computer processor and that sales guy told you that you needed a bigger cache memory? And you didn’t understand why you needed it? Well you still don’t, so don’t bother asking. I mean, what does that even mean? It’s not like you can feel the difference between a 5MB or a 10MB cache. It’s not like your computer will run any faster if you have a bigger cache. It doesn’t matter how fast your computer can handle a certain amount of data, because the cache memory is there to store the data for a very short period of time.

What is the difference between L1 L2 and L3 cache?

For high-performance computing, it is very important to have access to as much cache memory as possible. In a computer’s CPU, the cache memory is the small amount of memory between the CPU and the main memory. The cache memory is an important part of a computer’s architecture. There are basically three types of cache: L1, L2, and L3. First, you need to know that there are different levels of cache in your computer’s RAM. The level of cache is determined by the L1, L2 and L3 naming. L1 Cache is located on the processor itself. L2 cache is a little further away and is connected to the processor via the motherboard. L3 cache is the furthest away and is connected to the processor via the motherboard and the memory controller hub.

What is L1 cache used for?

L1 cache is a small amount of memory that can be found on the CPU. It’s the fastest memory that can be found on any of the computer hardware. It can be thought of as a small storage room that holds small pieces of data, such as where to find instructions for the CPU to execute. It’s a cache, because it stores data temporarily for faster access. One of a CPU’s most important components is its cache. The cache, which is sometimes referred to as L1 cache, is a small chunk of memory that is used by the CPU to store frequently used data and instructions. There are different types of cache and different levels of cache. A CPU can access data and instructions from its cache in a fraction of the time it takes to access the same data and instructions from RAM.

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