choose-launch-configuration

A CUDA launch-configuration guide for choosing the number of threads in each block and the number of blocks in a grid. CUDA is NVIDIA's system for running code on graphics processors.

In plain words
What is it for?
Use it when starting or tuning a CUDA kernel, including kernels with high resource use, persistent kernels, cooperative launches, or compile-time block-size choices.
Why use it?
It helps identify when a kernel's block or grid dimensions limit processor use, create idle tail work, or conflict with register and shared-memory needs.

Skill for Claude CodeCodex

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/tensormux/kernel-skills/choose-launch-configuration
Any agent
npx skills add tensormux/kernel-skills --skill choose-launch-configuration
Clone the repo
git clone --depth 1 https://github.com/tensormux/kernel-skills

Made for: Claude Code, Codex.

Per session 0 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,581 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 $0.00000 $0.03581
Opus 5 $0.00000 $0.01791
Sonnet 5 $0.00000 $0.00716
Haiku 4.5 $0.00000 $0.00358

Measured yesterday against content hash 69471d48d256, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

choose-launch-configuration 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 yesterday.

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/cuda/choose-launch-configuration/SKILL.md · 131 lines

How it starts

The opening of the file, as written. The whole thing — 131 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Skill: Choose CUDA Launch Configuration

Purpose

Guide the agent through selecting the correct and efficient thread block dimensions and grid dimensions for a CUDA kernel, covering occupancy analysis, register and shared memory constraints, tail effects, persistent kernels, and when to use cudaOccupancyMaxActiveBlocksPerMultiprocessor as a decision tool.

Use this when

  • Writing a new CUDA kernel and choosing the initial block and grid dimensions
  • A kernel is underperforming and you suspect the launch configuration limits occupancy or causes tail effects
  • Selecting block dimensions for a kernel with significant register or shared memory usage
  • Implementing a persistent kernel or a cooperative grid launch
  • Tuning a kernel where block size is a compile-time template parameter and you want to choose the best default

Do not use this when

  • The kernel's performance is dominated by a compute or memory bottleneck unrelated to occupancy: fixing the launch config will not help if the kernel is register-bound or has severe memory access inefficiency
  • The launch configuration is already determined by an API contract (e.g., cuBLAS, cuDNN, cooperative kernels with fixed grid requirements): do not override the library's choices
  • The block size is constrained by the algorithm's data decomposition to a specific value (e.g., exactly 32 threads for a warp-level primitive): respect the algorithmic constraint and do not change it to improve occupancy

Inputs the agent should gather first

  • Kernel register usage: from ptxas -v output, nvcc --ptxas-options=-v, or from Nsight Compute profiling. Registers per thread is the primary constraint on occupancy when register usage is high.
  • Static shared memory per block: declared __shared__ arrays. Size in bytes.
  • Dynamic shared memory per block: the third kernel launch argument. Size in bytes.
  • Problem size: total number of work items (elements, rows, output tiles, etc.). Determines the minimum grid size needed to cover all work.
  • Hardware target: SM architecture and SM count. Key occupancy limits differ by architecture. Also: the maximum threads per block (1024 on all current GPUs), the maximum blocks per SM (varies: 16–32 depending on SM gen), the register file size per SM (65536 32-bit registers on SM70+), the smem per SM.
  • Whether the kernel is latency-sensitive: for latency-critical single-sample inference, occupancy may matter less than minimizing launch overhead and maximizing L2 utilization for a fixed small grid.
  • Whether cooperative groups are needed: cooperative grid launches have additional constraints (entire grid must fit resident on the GPU).

Read the full file on GitHub · 131 lines

Files

What ships with it

1 file 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. yesterday First seen · 131 lines · 0 tokens per session scan A 69471d48d256

Subscribe to this mod's changes

choose-launch-configuration is a skill published in the GitHub repository tensormux/kernel-skills (70 stars, last pushed 2mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 3,581 tokens. 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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