Have you ever checked your Linux system's memory usage and panicked because it seemed like all your RAM was being used? Don't worry your RAM is fine! This video will explain how Linux manages memory, why it looks like your RAM is full, and why you shouldn't be concerned.
🙋♂️ Now the question is, what's Going On?
When you see high memory usage on Linux, it's primarily because of disk caching. Linux uses available memory to cache disk operations, making the system faster and more efficient. This cached memory is borrowed when not needed elsewhere and can be instantly released for applications when required.
🙋♂️ The next question is, why does Linux use disk Cache?
Disk caching improves system performance by keeping frequently accessed data in memory. This reduces the time it takes to read data from the disk, making the system more responsive. So what is the downside? It can confuse users into thinking their memory is low, but this isn't true.
🙋♂️ Let's understand How Memory is Managed
Linux categorizes memory usage as follows:
✅ Used Memory is the memory actively used by applications.
✅ Free Memory is the one not used at all.
✅ Available Memory is used by the disk cache but can be repurposed for applications instantly.
When you need to understand your system's memory, focus on the "available" memory rather than "free" memory.
🙋♂️ Another confusing question is, do You Need More Swap?
Probably not. Disk caching uses idle RAM and returns it to applications as needed. Swap is used when physical RAM is fully utilized. If applications require more memory, the kernel reallocates it from the disk cache, ensuring minimal swap usage.
🙋♂️ How to Verify Memory Usage
To accurately check your memory usage, use:
free -m comand
Look at the "available" column to see how much memory is actually available for your applications. This provides a true picture of your memory usage.
🙋♂️ The important question is When to Worry.
While disk caching is generally beneficial, there are signs of genuine low memory:
✅ Available memory is nearly zero.
✅ Increasing or fluctuating swap usage.
✅ The o o m killer is active, which can be checked with dmesg.
🏁 to sum up
Understanding how Linux manages memory can alleviate unnecessary worry about your system's performance. Disk caching makes your system faster and more responsive, and the memory used can be reclaimed for applications instantly. Focusing on "available" memory gives you a clearer picture of your system's health.
🖼 Image ref: https://www.linuxatemyram.com/atemyram.png
📚Book link:
https://pratimuniyal.gumroad.com/l/cracking-the-devops-interview
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