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AWS engineer reports PostgreSQL perf halved by Linux 7.0, fix may not be easy

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PostgreSQL performance regression on Linux 6.0, critical infrastructure issue for cloud/database engineers.

2026-04-05 cloud Hacker News (100+)
AWS engineer reports PostgreSQL perf halved by Linux 7.0, fix may not be easy
Summary

Linux 7.0's restriction to full and lazy preemption models causes PostgreSQL throughput to drop to 0.51x on Graviton4 due to increased spinlock wait times. An AWS engineer proposed restoring PREEMPT_NONE, but kernel maintainer Peter Zijlstra insists PostgreSQL must adopt RSEQ time slice extensions. With Linux 7.0 stable releasing in two weeks and powering Ubuntu 26.04 LTS, this regression may persist until PostgreSQL updates.

Key Takeaway

Benchmark your PostgreSQL deployments against Linux 7.0 kernels now and plan to enable RSEQ extensions or lobby for upstream patches to avoid production degradation.

Why it matters

PostgreSQL is a staple in cloud-native data layers, and a 50% throughput drop from kernel changes threatens the scalability and cost-efficiency of services you architect on AWS or GCP infrastructure.