Linux 5.15 Adds New Syscall to More Quickly Free Memory of Dying Processes

phoronix.com

11 points·rbanffy··7 comments

I like how the jargon "memory pressure" has taken over where we once used the logical term "low memory". Computing becoming less accessible before our very eyes!

It's "jargon" related to memory management development that describes a different condition.

You can run just fine with very low memory if there is no memory pressure. No allocation demand means no requirement to perform costly reclaiming operations.

It's worse than jargon because there seems to be no clear definition. It seems to be loosely defined as "how much swap space you're using" by some people, at least.

It's not defined that way by people who use it in kernel development. It has at least as clear a definition as "low memory" and refers to something different, as I said.

Why not simply more quickly free memory of every dying process?

There are more details in https://lwn.net/Articles/864184/. I already forgot why it's necessary, but I know the article explains it.

For the record: "The killed process is, itself, responsible for cleaning up and freeing its resources, a task that is carried out in kernel context. If, however, the killed process finds itself blocked in an uninterruptible sleep, that cleanup work could be delayed indefinitely. There are other factors that can slow down the freeing of memory, including how busy the relevant CPU is and whether that CPU is running in a slow, low-power state."

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