Problems / LLM serving, easy

Token quota at launch

A chat product sends 2,000-token prompts at 50 requests a second. The provider allows 4 million input tokens a minute.

Free to open. Runs in your browser, no sign-up.

Your goals

Success ≥ 99%, time to first token p99 ≤ 2.5 s.

The traffic

50 requests a second for 30 seconds: 100% request (reads).

The system

What each component does in this design, and what calls it. The simulator mimics each one from these settings.

ComponentIts job hereSettings
Load balancerLoad balancerTraffic enters here.Calls AI app.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
AI appApp serviceLoad balancer forwards to it.Calls Model.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 30 s
ModelLLM endpointAI app calls it.Latency has two parts: time to the first token, then a steady stream of tokens per second.400 streams · 4M input tokens/min

Hints

Try it first. Open one hint at a time if you get stuck.

Hint 1

Look for 429s on the model.

Hint 2

50 × 2,000 × 60 = 6 million tokens a minute.

Hint 3

Most of each prompt is the same system prompt.

One way to solve it

Enable prefix caching: cached prompt tokens are cheaper and do not count toward the quota.

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