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What Is Ramp-Up in Load Testing?

2 min read
Loadcurl
Loadcurl
Loadcurl Team

Ramp-up is the time your load test spends climbing from little or no traffic to the target RPS. It is one of three core knobs in an HTTP load profile — alongside target RPS and duration.

In Loadcurl, ramp-up is configured in seconds. 0 means start at full target RPS immediately.

The three knobs​

KnobMeaning
Target RPSPeak requests per second you want to reach
Ramp-upSeconds to go from 0 → target
DurationTotal length of the run (seconds)

Example: duration 600s, ramp-up 60s, target 200 RPS → roughly one minute of climb, then about nine minutes near peak (exact shape depends on the generator schedule).

Why ramp-up matters​

Starting at full blast mixes different failure modes:

  • Cold caches and empty connection pools
  • Autoscalers still waking up
  • JIT / runtime warmup
  • Sudden lock or queue shocks

A short ramp-up lets the system enter a steady state so p95/p99 during the hold reflect capacity — not just cold-start drama.

Choosing a ramp-up​

Practical starting points:

  • Smoke / debug: 0–15 seconds
  • Normal load test: 30–120 seconds
  • Higher RPS or autoscale validation: 60–180+ seconds

If your pass criteria care about steady-state latency, either use a non-zero ramp-up or ignore the first portion of the run when comparing percentiles.

Ramp-up is not duration​

Teams sometimes set a long duration and forget ramp-up — or set ramp-up equal to duration and never reach a stable hold. Prefer:

  1. Enough ramp to warm
  2. Enough remaining duration to measure at target RPS

See How Many Requests Do I Need for a Meaningful Load Test?.

Quota impact​

Loadcurl still places a hold of roughly duration × RPS when you start (minimum 1). Ramp-up does not shrink that reservation formula — plan Usage accordingly.

Common mistakes​

  • Ramp-up 0 on a production game day
  • Comparing p99 from a zero-ramp run to a 2-minute-ramp run without noting the difference
  • Ramp longer than the whole test, leaving no steady hold

In the product​

On New test, set duration, ramp-up, and target RPS (capped by plan). Paste curl / Postman or fill the composer, verify the domain, then start.

Docs: Getting started · Core concepts

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