hz-simpleperf-debug

hz-simpleperf-debug is a skill for Claude Code, Codex from meta-quest/agentic-tools. It costs 50 tokens per session (1,729 once invoked), scanned A, original, Apache-2.0.

A profiling guide that uses simpleperf to measure where a Meta Quest or Horizon OS app spends processor time.

In plain words
What is it for?
Use it to find CPU-heavy functions, compare kernel and application work, and investigate cache misses or branch-prediction problems.
Why use it?
It distinguishes processor, memory, and input/output bottlenecks and exposes hardware issues that ordinary software traces may miss.

Skill for Claude CodeCodex

Part of the agentic-tools plugin — 29 skills, 1 hook, 1 MCP server shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/meta-quest/agentic-tools/hz-simpleperf-debug
Any agent
npx skills add meta-quest/agentic-tools --skill hz-simpleperf-debug
Clone the repo
git clone --depth 1 https://github.com/meta-quest/agentic-tools

Made for: Claude Code, Codex.

Or install agentic-tools, the plugin that ships this one along with the rest of its 29 skills, 1 hook, 1 MCP server.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for hz-simpleperf-debug

README.md
[![agentmods](https://agentmods.dev/badge/skills/meta-quest/agentic-tools/hz-simpleperf-debug.svg)](https://agentmods.dev/skills/meta-quest/agentic-tools/hz-simpleperf-debug)
Your own site
<a href="https://agentmods.dev/skills/meta-quest/agentic-tools/hz-simpleperf-debug"><img src="https://agentmods.dev/badge/skills/meta-quest/agentic-tools/hz-simpleperf-debug.svg" alt="Measured on agentmods" height="20"></a>
Per session 50 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,729 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00050 $0.01729
Opus 5 $0.00025 $0.00864
Sonnet 5 $0.00010 $0.00346
Haiku 4.5 $0.00005 $0.00173

Measured 4d ago against content hash 3b1bb49cb1e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

hz-simpleperf-debug scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 4d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/hz-simpleperf-debug/SKILL.md · 185 lines

How it starts

The opening of the file, as written. The whole thing — 185 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Simpleperf Debug Skill

When to Use

Use this skill when you need hardware-level CPU performance insights on Meta Quest devices:

  • Classifying whether an app is CPU-bound, memory-bound, or I/O-bound
  • Finding CPU hotspot functions consuming the most cycles
  • Measuring kernel vs userspace CPU overhead per thread
  • Identifying cache-thrashing or branch-prediction issues
  • Supplementing Perfetto trace analysis with hardware PMU counter data

This skill complements hz-perfetto-debug. Perfetto shows what your app is doing over time. Simpleperf shows where the CPU is spending hardware cycles — cache misses, branch mispredictions, and instruction throughput that Perfetto can't see.

VR Performance Context

Quest devices run on mobile ARM SoCs with strict thermal and power budgets. CPU-bound apps hit frame drops when:

Refresh Rate CPU Frame Budget Notes
120 Hz 8.3 ms Tight — simpleperf critical for finding hotspots
90 Hz 11.1 ms Default target for most apps
72 Hz 13.9 ms Fallback for heavier apps

Simpleperf's hardware counters reveal bottlenecks invisible to software tracing.

metavr Setup

Simpleperf profiling is powered by the metavr CLI. Invoke via npx — no install required:

npx -y metavr --version

Examples below use the bare metavr command for brevity. If metavr is not on PATH, invoke the same CLI via npx -y metavr <args> (the CLI is published under the npm package metavr). Connect your Quest via USB with developer mode enabled.

Quick Start Workflow

1. Classify the Workload

Before optimizing, determine the bottleneck type:

# Classify the foreground app's workload (10-second sample)
metavr perf simpleperf classify

# Target a specific app
metavr perf simpleperf classify --app com.example.myapp

# Custom duration
metavr perf simpleperf classify --duration 15

Returns a classification with evidence:

Classification Indicator Optimization Strategy
CPU-bound High IPC, low stall ratio Optimize algorithms, reduce draw calls, batch work
Memory-bound High stall ratio (stalled-cycles-backend / cpu-cycles) Reduce cache misses, improve data locality, shrink working set
I/O-bound High context switches per second Reduce blocking I/O, use async, minimize thread contention

Read the full file on GitHub · 185 lines

Files

What ships with it

3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 4d ago First seen · 185 lines · 50 tokens per session scan A 3b1bb49cb1e5

Subscribe to this mod's changes

hz-simpleperf-debug is a skill published in the GitHub repository meta-quest/agentic-tools (187 stars, last pushed 12d ago), licensed Apache-2.0. It adds 50 tokens to every session and 1,729 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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