Modern computers and smartphones use very elaborate systems to ensure consistent performance of the machine. There are 3 types of memory typically used in these devices, the main storage or hard drive, RAM, and cache memory. All serve different purposes, with the cache being the least in volume but used the most frequently. In this article, we’ll discuss what is cached data, on both computers and smartphones.
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What Does Cache Data Mean?
The cache is a type of storage, both hardware, and software-based, that is used to serve requests from processors extremely fast. It is temporary storage, like a clipboard, and can be cleared. Cache data and cache memory differ and aren’t the same. It is situated close to the processor or inside it, and it can be cleared. Among all the storage types, the cache is the smallest one but functions the fastest. We can get a maximum of 8 to 12 MB of cache volume from general processors like Intel.
Cache stores data that are used most frequently, and some read/write commands so that when these are requested, it can present them at the highest speed, ensuring faster execution. Processors check for data in cache before in various types of RAM. So, bigger cache memory is a preferable choice for buying processors.
Types of Cache Memory
There are 3 types of the cache according to the allocation method.
Level 1 Cache
This is separate for each processor core. It’s the smallest and fastest among the 3, having a cache memory size of 2KB to 64KB. It is made from registers. It is made inside the processor.
Level 2 Cache
Like Level 1, this is also different for each core, having a volume of 256KB to 512KB. It can be both inside the processor or close to it, built on an IC. It is connected to the processor with a high-speed bus, to ensure faster access.
Level 3 Cache
This consists of the biggest volume of 1MB to 8MB and is shared between processor cores. It is the slowest among the 3, still approximately 2 times faster than RAM.
According to the writing method, we get 3 more types.
Write-through caches
Here, cache and memory update data simultaneously. It is a reliable yet simple method that also enables data recovery. But cache latency occurs here because writing is done in 2 places at once.
Write-back caches
In this type, data is only updated in the cache, not in the main memory. Here, data recovery possibility is scarce but the speed of writing is very fast.
Write-around Caches
Here, the machine writes cache data directly into the memory, and cache memory stays unchanged. This becomes useful in various places like app cache in Android smartphones.
These are the basic types of cache data. There are 2 terms to define if the cache memory is useful or not.
- A cache hit occurs when the computer can find the requested data right inside the cache memory. In this stage, the process is done very quickly. The hit ratio or hit rate is the amount of cache hit occurrence per request, in percentage.
- A cache miss occurs when the processor can’t find the needed data on the cache. As it checks into cache before going to the RAM, cache miss results in latency with a slower result. Cache latency is the phenomenon of the delayed process due to not finding data inside the cache when checking.
Buffer vs Cache
Buffer and cache work on the same principle, both of them are storages for temporary usage. The difference is, the buffer is situated in RAM, and CPU stores temporary data here, while the cache is a part of the hard drive (disk caching) or main memory (memory caching).
The cache is a high-speed storage area made of static RAM. But buffer is made of ordinary dynamic RAM that is running inside a computer. The workflow also differs. The cache is used during read/write processes but the buffer is used in input-output processes.
Cache Coherency
In a high-performance multiprocessor system, or distributed shared memory (DSM) system, the multiple processors can attempt to read/write in the same cache location. Cache Coherency enables these processors to be coherent when attempting such operations to prevent data overlapping.
What is Cache Data on Android?
Like computers, Android, or any other smartphone platforms use cache memory with their processors. The difference is, there’s another form of cache in smartphones which is located at the main memory or internal storage. Unlike traditional cache data, these caches can take more than a gigabyte of free space on your phones. In PCs and smartphones, you can clear cached data.
This cache memory fills up by storing app data and browsing information, in order to give you a smoother experience and faster loading of apps. For example, thumbnails of the gallery are stored to generate previews of photos. So every time you launch the gallery, it doesn’t need to load all the media again, thus saving battery life and processing power. Or, the Facebook app, in which you can scroll through some pages initially without the internet because they were pre-loaded in the cache.
In modern days, we can store app cache to both the main storage and SD card. This feature is enabled from Android v4.4 and is a very useful one to maintain internal memory. By default, the cache location in main storage is “/data/data/<package_name>” and location in SD card is “Android/data/<package_name>”.
Cleaning cached data isn’t a viable solution to save space, because it makes apps load slower, and as soon as you load them, the cache is generated again. But if you’re running critically low on storage space, cleaning cache can free up a lot of space. You can clean the app cache for different apps, and clear browser cache too.
Conclusion
In this article, we’ve shown you a brief introduction to what is cached data. In computers and smartphones, cache data is a small but crucial element to ensure faster performance and loading of software. Cache memory volume can’t be changed or upgraded, which is why it is often better to look for a processor with higher cache volume if you’re looking for optimized constant performance.
