One pet peeve I have with virtual memory management on Linux is that, as memory usage approaches 100%, the kernel starts evicting executable pages because technically they're read-only and can be loaded from disk. Thus, the entire system grinds to a halt in a behavior that looks like swapping, because every program that wants to execute instructions has to load its instructions from disk again, only to have those instruction pages be evicted again when context switching to another program. This behavior is especially counter intuitive because disabling swap does not prevent this problem. There are no convenient settings for administrators for preventing this problem.
It's good that we have better swapping now, but I wish they'd address the above. I'd rather have programs getting OOMKilled or throwing errors before the system grinds to a halt, where I can't even ssh in and run 'ps'.
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