> Maybe we should, but requiring the use of a new low level facility that was introduced in the 7.0 kernel, to address a regression that exists only in 7.0+, seems not great.

Completely right. This sounds like a communication failure. Maybe Linux maintainers should pick a few applications that have "priority support" and problems with these applications are also problems with Linux itself. Breaking Postgres is a serious regression.

Reminds me of a situation where Fedora couldn't be updated if you had Wine installed and one side of the argument was "user applications are user problem" while the other was "it's Wine, like come on".

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falcor84 8 hours ago | parent [-]

I for one liked the old and simple WE DO NOT BREAK USERSPACE attitude.

https://linuxreviews.org/WE_DO_NOT_BREAK_USERSPACE

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gcr 7 hours ago | parent | next [-]

Performance regressions are different from ABI incompatibilities. If the kernel refused to do any work that slowed down any userspace program, the pace would go a lot slower.

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shadowgovt 5 hours ago | parent [-]

Or be a lot uglier. See: Microsoft replacing its own API surfaces with binary-compatible representations to workaround companies like Adobe adding perf improvements like bypassing the kernel-provided kernel object constructors because it saved them a few cycles to just hard-code the objects they wanted and memcpy them into existence.

	▲	cogman10 3 hours ago \| parent [-]
		Microsoft's whole "Let's just ship all the dlls" attitude is a big part of the reason a windows install is like 300GB now. Eventually you'd expect that something has to give.

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reisse 7 hours ago | parent | prev [-]

Not sure it is true anymore. I've encountered few userspace breaks in io_uring, at least.