What’s the cache, exactly? You probably hear the word quite a lot when you use a phone or computer. And you might not have given much thought to what it means – even while you’re doing carry out tasks like clearing your cache. So, let us reveal all, with this handy guide explaining all you need to know about caches…
Cache meaning – in a nutshell
A cache is a temporary storage area (on a computer, mobile phone or other device) that stores data so that future requests for that data can be served faster.
A cache stores copies of frequently accessed data in a location that’s closer to the end request or job, which reduces the time it takes to fetch the data from its original source. Caches can be found in both hardware and software systems, and they play a crucial role in improving system performance and efficiency.
Caches in hardware
Caches are often integrated into processors, where they store copies of instructions or data from main memory. This helps reduce the time it takes for the processor to access this data, speeding up system performance.
Caches in software
Caches can also store copies of web pages and other types of data for a software program. For example, web browsers use caches to store copies of web pages, images, and other resources locally on your device. This allows the browser to load web pages faster next time you visit, as it doesn’t have to re-download data from the internet.
How does a cache work?
When a processor or software application requests data, the cache checks if a copy of that data is already stored locally.
If the data is found in the cache (that’s a cache hit!), it’s retrieved and provided to the requester quickly.
If the data isn’t in the cache (that’s a cache miss. Boo!), the system retrieves it from the original source and stores a copy in the cache for future use.
Caches use various clever algorithms to manage the data they store, including least recently used (LRU) and first in first out (FIFO). These algorithms play an important part in deciding which data is kept in the cache, and which data gets chucked out to make room for fresh new data.
Types of cache
There are a few different types of cache used in computing systems. Here’s a quick rundown of each:
L1 cache. Also known as the primary cache, this is the smallest and fastest type of cache. It’s typically integrated directly into the processor core.
L2 cache. This is larger than the L1 cache, and usually located on the same chip as the processor. It’s a middle ground between the fast L1 cache and slower main memory (RAM).
L3 cache. Larger than L2 cache, the L3 is shared among multiple processor cores. It helps improve performance by allowing different cores to access shared data more quickly.
Disk cache. This is used to temporarily store data from a hard disk or solid-state drive (SSD), and plays an important part in improving overall disk performance.
Flash cache. Also known as an SSD cache, this is used to accelerate read and write operations on a slower storage device, such as a traditional hard disk drive.
Browser/app cache. Browser and app caches store copies of frequently accessed web pages, images, and other resources locally on the user's device. This allows browsers and apps to load content faster on return visits.
Benefits of using a cache
Using a cache helps you out in lots of different ways. Here are a few of the most important:
Faster access times. By storing frequently accessed data closer to the requester, caches reduce the time it takes to fetch data from its original source, which leads to faster access times.
Reduced latency. Caches help reduce latency by minimising the time it takes for the processor or software application to access data – especially when the data is located on slower storage devics such as hard disks or SSDs.
Improved efficiency. Caches help improve system efficiency by reducing the need to access slower storage devices or remote servers for frequently accessed data.
Better user experience. Caches allow programs, web browsers, and other software applications to load data faster, resulting in a smoother and more responsive performance. That means less annoying lag and frozen screens.
What are the drawbacks of using a cache?
Okay, so we’ve talked about the benefits of using a cache – but there are also some potential drawbacks worth bearing in mind:
Consistency. Caches rely on the assumption that the data they store stays unchanged between accesses. So if the underlying data is changed by another process or user, the cache will contain stale or outdated information, which could lead to inconsistencies.
Invalidation. Caches need to be updated or invalidated when the underlying data changes. This is essential for maintaining data consistency, but it’s a challenging task for a lot of computing systems. Sometimes it’s not 100% accurate.
Size limitations. Caches can only store a limited amount of data at a time. As a result, they need to be carefully designed to make sure that only the most relevant data is retained.
Cache warming. When a cache is first initialised or cleared, it may take some time to fill. This can sometimes slow things down.
Cache FAQs
Is it OK to clear cached data?
Clearing cached data is totally fine and can actually help your device's performance. It frees up space and can also resolve issues with apps or websites not loading correctly.
How often should I clear my cache?
As for how often to clear your cache, it really depends on your usage patterns. If you notice your device slowing down or apps misbehaving, it might be a good time to clear the cache. Some people do it once a month, while others do it more frequently.
What happens if I clear my cache all the time?
If you clear your cache all the time, you might experience slightly longer load times for websites and apps since they'll have to re-download certain data. However, it can also keep your device running smoothly and free up storage space. Just find a balance that works for you!
