Linux kernel 7.0 delayed over postgresql performance issue

Linux creator Linus Torvalds is unlikely to be pleased with a recent discovery just days before the highly anticipated Linux 7.0 release.

Performance issue in postgresql affects kernel 7.0

After weeks of beta testing with thousands of volunteers worldwide, Linux 7.0 is expected to arrive mid-April. For rolling release users, they'll get it almost instantly, but beware, as it could still be delayed. A crucial error has been detected affecting PostgreSQL's performance directly. An Amazon Web Services engineer raised the alarm, finding the database's speed reduced by almost half in kernel 7.0.

PostgreSQL is one of the world's most widely used database systems, in both enterprise and individual projects. Such a drop could impact thousands of services.

Kernel change causes internal timing issue

The problem stems from a kernel internal change. Specifically, an option called PREEMPT_NONE, influencing how the system handles certain CPU tasks, has been removed. It's been discovered that up to 55% of CPU time is lost in internal waits, rather than processing data. In essence, the computer works harder but delivers less.

Developers now face a dilemma. The quickest solution would be to revert the change and go back. However, that's not as simple as it sounds. Undoing it would undo part of this week's kernel work. Moreover, it wouldn't solve the underlying issue, which could resurface with future changes.

Instead, developers are proposing PostgreSQL adapt, specifically using a different internal timing system, rseq. However, this solution isn't immediate, requiring urgent PostgreSQL changes that may not be ready in time for the official Linux 7.0 release.

Given this, there's no word yet of delays, but this last-minute issue undoubtedly has Linus Torvalds on edge. The planned calendar still points to a mid-April stable release, around 10 weeks since 7.0-rc1. Some estimates predict possible official release dates of April 5th, 12th, or 19th, depending on the number of remaining RCs.

For those preferring a safe bet, Ubuntu 26.04 will be the gateway to this new era. For early adopters, Linux 7.0-rc7 is available for testing, thanks to tools like Mainline, which allows easy installation of different kernel versions.