Cache

What Is Cache?

In a computer environment, a cache is a type of high-speed memory that can temporarily store data, usually embedded in computer hardware or in application software.

In a sense, a cache is actually a smaller, more expensive but faster memory that retains commonly used data to significantly decrease the retrieval time for that data on subsequent accesses, thereby enhancing the overall performance of the computer. As a result, CPUs, various applications, operating systems, etc. use and rely on caches.

How Cache Works？

When processing data, the CPU first checks the cache. If the required data is in the cache, stored from a previous operation, it avoids the slower process of reading from main memory. Access to main memory is significantly slower than the CPU's speed, leading to idle CPU cycles and wasted time if the cache is not utilized.

When the CPU finds the needed data located in the cache, it is called a cache hit. However, due to its limited size, cache can only hold a fraction of the data from memory, leading to a possibility of a cache miss. When a miss happens, the CPU goes to memory to process the data, and copies it into the cache for the next convenient access. This also means that the data in the cache is not set in stone.

The content stored in the cache is the most frequently accessed data over a period of time, which will be found to change with the user's usage habits. So the data in the cache must often be replaced according to a certain algorithm to maximize the computer's processing efficiency.

Of course, in addition to computer hardware, cache is also widely used in applications and software. This type of cache stores data or files related to the program, and browsers like Safari and Chrome, for example, use browser cache to improve web performance and speed up the refreshing of web content.

Pros and Cons of Cache

Advantages

・Increase Speed

Keeping data in a cache reduces the time the computer spends retrieving data and dramatically increases operating speed.

・Run Offline

Cache enables apps to function offline, like allowing continued playback of a YouTube video for a short period even after an Internet disconnection.

・Saving Resources

In addition to improving device performance, fast access can help users save resources such as power and bandwidth.

Disadvantages

・Physical Damage

A cache is essentially a computer component that exists in a physical sense, so there is always the possibility of device corruption.

・Outdated Information

Stale data in the app cache can lead to app malfunctions or outdated information, such as Chrome displaying an old version of a web page due to the cache not being refreshed with the latest data.