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Buffer vs. Cache


What Is Buffer?

A buffer is a temporary area where data is stored in the main memory (RAM) or disk while moving from an input system to an output system. Buffers make it possible for tasks to be completed and information to be passed between the two regardless of speed disparities, the pace at which data is received or processed, or the priority of the processes. Thus, both sender and receiver can carry out their own commands and adjust to the computing variations of each other without any interference. (kbeautypharm)

Without buffers, the faster endpoint has to either wait for the slower one or lose data.

Here are a few examples where buffers are used:

  • Video streaming: Your system retrieves and downloads a few bytes of video from the server when streaming. As these bytes are being played, more bytes are being stored and prepared to be played. This enables your system to play the movie directly from its memory rather than from the server. Thus, your video stream will continue uninterrupted as long as there is data in the buffer.
  • Data buffering between the I/O module and processor: Data is sent and buffered in the I/O module before being transferred to the external device at its desired pace due to the high I/O request transfer rates into and out of the main memory. This lowers the expense of processing overhead as well.
  • Kernel buffer: When an application writes to disk, it’s usually up to the kernel to decide whether it writes to disk or into a buffer. Eventually, buffers are synchronized to disk, which is more efficient because the kernel can batch multiple writes in one go. The buffer sequence also ensures that data that has to be written can be found and filled during the operation.

What Is Cache?

A cache is a storage location where an application temporarily stores data to reduce data access time and latency. Cache memory is stored in RAM or a disk, called memory cache and disk cache, respectively, to obtain copies of certain processes to improve data access.

Caches are used everywhere: from the CPU that needs access to very fast memory (L1, L2 and L3 caches) to data transferred over the Internet (CDNs). Content delivery networks (CDNs) are the caching portions of websites that enable users to load most of their data from servers geographically closer to them.

Unlike the original data source, which is exhaustive and stores everything, the cache memory only temporarily stores a subset of the data in memory until it needs to be re-accessed. Thus, every time an application requests data, it first checks the cache memory; if the data is located, this is referred to as a cache hit; otherwise, this is referred to as a cache miss, and the application will then check the original source.

Some examples of cache include

  • Web browser cache stores data on your local computer so it can be easily accessed;
  • Data from frequently visited pages is saved in the proxy cache so it can be quickly retrieved;
  • Gateways or reverse proxies, can be application-specific and cache responses from otherwise busy servers;
  • Application caches are used to define what can be cached and made accessible to users offline in web applications.

What Are the Differences Between Buffer and Cache?

Although buffer and cache share some similarities, they differ in a few ways:

Used between processes to increase efficiency and account for speed differences.Used to store frequently accessed data in order to reduce latency when needed.
Matches the speed between two devices and processes.Speeds up access to data frequently used or visited.
Stores the original data to be sent to the receiver.Stores a copy of the original data.
Used for input and output processes.Used to temporarily store data used by applications.

Since both buffers and caches have an impact on latency, we’ll need to monitor them to ensure good performance.

Buffer/Cache Monitoring with Sematext

Both buffers and caches come in multiple flavors. Some are closer to the infrastructure, like the buffers and caches used by the Linux kernel. Others are higher-level, for example, if you use RabbitMQ or Kafka as buffers between services. Or maybe you want to monitor the caches used by data stores like PostgreSQL or Solr.

With Sematext Monitoring, you can monitor all these and more. Sematext Monitoring is an infrastructure monitoring tool that allows you to explore multiple facets of your environment, alerting you when a metric has an anomalous value.

Sematext Monitoring is part of Sematext Cloud, an all-around observability platform. With Sematext Cloud, you can go beyond monitoring your own infrastructure, for example, by monitoring your website and showing you how much is loaded from the browser cache.

Give it a try. Use the 14-day free trial to test it out and see how it can help ensure the performance of your system.

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