AWS Engineer Reports PostgreSQL Performance Halved by Linux Kernel 7.0

A Critical Performance Regression in the Linux Kernel

An AWS engineer has reported a significant performance regression affecting PostgreSQL on the upcoming Linux kernel 7.0. According to the report, database performance can drop by as much as 50% under certain workloads.

The Issue

The regression was identified in the memory management subsystem of Linux 7.0, specifically affecting PostgreSQL workloads with high concurrent connection counts, memory allocation patterns common in database operations, and I/O scheduling changes introduced in the new kernel.

Why This Matters

PostgreSQL is the backbone of countless enterprise applications and cloud services. A 50% performance degradation would have cascading effects on cloud providers (AWS, Google Cloud, Azure), enterprise applications in banking and e-commerce, and cost implications for infrastructure.

The Fix Challenge

The engineer noted that the fix "may not be easy," suggesting the regression is deeply embedded in architectural changes to the memory management system rather than a simple bug.

Recommendations

For organizations running PostgreSQL: monitor kernel upgrade plans, benchmark workloads before upgrading, and consider staying on 6.x LTS kernels.

Source: LKML, Hacker News