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by pron 7 days ago
> Isn’t that only true though specifically at 100% CPU utilization?

No. Because any RAM access requires CPU, using up any CPU effectively captures some ability to use RAM.

> I don’t see how you can map X% CPU utilization to Y% RAM capture.

You're right that there isn't a fixed formula, but the most efficient balance can have a narrow range, because CPU and RAM are typically sold as a package with a rather narrow RAM/core ratio (usually between 0.5 and 4GB, where the lower end is usually when you have slow cores). This is also because of the intrinsic relationship of RAM and CPU.

> Like a program could be network heavy, CPU light and mmaps a large file? Or streaming a file from disk with a constant memory allocation, but doing heavy nonstop CPU work.

A program that is very CPU light can't make use of a lot of physical RAM at any one time (again, because using RAM requires CPU). Once exception is caching, but memory access patterns for caching are easily detectable, and you can (and Java does) offer a different balance for them. I covered that in my talk, which will be eventually published on YouTube.

1 comments

> I covered that in my talk, which will be eventually published on YouTube.

Any idea how I get myself notified once it’s up? Or a YT account to poll

https://www.youtube.com/java

Don't confuse it with the interview about my talk, which is already up, but doesn't cover any of the important details.