Warm cache and Hot cache on CPU

Did you know that there is the term of warm cache and hot cache on CPU?

Published on: May 11, 2020 by Website Admin

If you did than this small and beautiful blog {build for speed 😊} is not for you. You are too smart! This is for someone like me who buy's some books (from this guy of course) from time to time and starts to read and finds out that there is the term of "warm cache", "hot cache" and "cold cache" on CPU.

What does that mean you ask?

Well that means if you have a small Linux server running with Nginx and some MySQL (old school) you will not see the best performance on your server until it has been running for more then 24 hours.


Because it takes that long for the L1 cache on the CPU to optimize by the kernel and keep most important data needed for your applications to run well.

There are multiple types of "warm cache"

Cold cache: A cold cache is empty, or populated with unwanted data. The hit ratio for a cold cache is zero (or near zero as it begins to warm up).
Hot cache: A hot cache is populated with commonly requested data and has a high hit ratio, for example, over 99%.
Warm Cache: A warm cache is one that is populated with useful data but doesn’t have a high enough hit ratio to be considered hot.
Warmth: Cache warmth describes how hot or cold a cache is. An activity that improves

The above info is from: Systems Performance, Enterprise and the Cloud – Brendan Gregg