AWS Engineer Reports PostgreSQL Performance Halved By Linux 7.0, But A Fix May Not Be Easy

[erek]

"While fixing an active performance regression, it looks like this change to restore PREEMPT_NONE as the default preemption model might not be picked up. Peter Zijlstra who authored the original code simplifying the preemption modes has responded that the "fix" is to make PostgreSQL make use of the Restartable Sequences (RSEQ) time slice extension. That time slice extension support was also upstreamed for Linux 7.0.

"The fix here is to make PostgreSQL make use of rseq slice extension:

https://lkml.kernel.org/r/20251215155615.870031952@linutronix.de

That should limit the exposure to lock holder preemption (unless PostgreSQL is doing seriously egregious things)."

So if that stands and shifting the blame to PostgreSQL, Linux 7.0 stable could lead to a significant drop for PostgreSQL performance in some scenarios until that popular database server is updated.

Linux 7.0 stable is due out in about two weeks. This is also the kernel version powering Ubuntu 26.04 LTS to be released later in April."

Source: https://www.phoronix.com/news/Linux-7.0-AWS-PostgreSQL-Drop

 

[Vermillion]

Not a big deal. Anybody using any database isn't on the latest kernel anyways. Poatgres devs have plenty of time to fix the issue.

 

[erek]

Not a big deal. Anybody using any database isn't on the latest kernel anyways. Poatgres devs have plenty of time to fix the issue.

Hope

 

[Vermillion]

Hope

You won't see RHEL or Ubuntu LTS using that kernel anytime soon. Only rolling distributions like Arch will maybe see this issue and if you're using rolling distros for production....well may God have mercy on your soul.

 

[jardows]

Anyone want to bet that some Oracle devs are significant contributors to 7.0 kernel?