AWS Engineer Reports PostgreSQL Performance Halved By Linux 7.0, But A Fix May Not Be Easy
Summary
AWS/Amazon engineer Salvatore Dipietro reports that Linux 7.0 development kernel halves PostgreSQL throughput on Graviton4 due to increased user-space spinlock contention. A patch to restore PREEMPT_NONE was proposed, but a lasting fix may require PostgreSQL to adopt the Restartable Sequences (RSEQ) time-slice extension, which could delay performance improvements. Linux 7.0 stable release is nearing, with potential implications for PostgreSQL performance on Ubuntu 26.04 LTS until updates arrive.