Brendan Gregg USE+TSA Performance Analysis

Overview

A fixed, evidence-first procedure for system performance debugging, root-cause analysis (RCA), and incident reporting, distilled from Brendan Gregg's published methodologies. Instead of running whichever commands happen to be familiar, the agent poses questions first and then finds metrics to answer them: the USE Method (Utilization, Saturation, Errors) sweeps every resource, the TSA Method (Thread State Analysis) decomposes thread time, and off-CPU analysis plus flame graphs drill into what the sweeps find. Every investigation ends in a structured triage note, RCA report, or postmortem where each claim traces to a command and its output.

This skill adapts material from the community repository thecsdoctor/brendangregg-use-tsa-skill (full checklists, reference library, and report templates live there).

When to Use This Skill

• Use when a server, VM, or container is "slow" and the cause is unknown
• Use when latency or throughput regressed after a deploy, config change, or load shift
• Use when CPU, memory, disk, or network metrics look abnormal and need interpretation
• Use when an application hangs or threads pile up
• Use when the user asks for debugging, triage, or root-cause analysis of a performance issue
• Use when an incident needs an RCA report or a blameless postmortem with an evidence trail