Run stepped HTTP load tests with ab/wrk, ramping concurrency levels to collect p50/p90/p99 latency, detect performance inflection points, and recommend optimal concurrency. Triggered by requests like 'load test this URL', 'benchmark my API', 'find the max concurrency', or mentions of p99 latency, throughput saturation, or capacity planning.
SkillScore100Maintained
Automatic
◆QA & Test Engineering pack
Last verified 8/10/2026
What it changes
Passed 20 of 20 test cases with the skill, and 10 of 20 without it.
Without skill48%
With skill100%
Checks it passed that the model alone missed
Identifies the key name as step_index
Requires RPS growth to be less than 10%
Requires p99 latency growth to exceed 50%
and 14 more in the full report
12 fixed11 passed either way0 still failing0 broke
Pass-rate lift
+52 pp
Tokens
+17%
Agent turns
0%
Response time
-64%
Model gemini-3.6-flashMeasured 8/10/2026v123 of 23 cases passed with skill · 20 comparable
Tokens, turns and time describe resource use, not a dollar price.
See it in action
One of 9 test cases the skill fixed. Same model, same prompt, with and without the skill.
1 of 9
Prompt
When inspecting the JSON output format of the profiler under the `inflection_points` top-level array key, what field contains the zero-based sequence position of the step where the inflection occurred?
What was checked, without and with the skill
Checked
Without skill
With skill
Identifies the key name as step_index
Missed
Passed
case-14 · gemini-3.6-flash · 8/10/2026 · answers are capped and redacted
What's inside
The instructions your model reads when the skill loads.
SKILL.md143 lines2 filesincludes scripts
HTTP Load Profiler — Stepped Concurrency Load Test + Inflection Point Analysis
Run stepped concurrency load tests against HTTP services, automatically collect latency percentiles, and detect performance inflection points.
Features
Dual engine support: Auto-detects wrk (preferred) or ab (Apache Bench); manual override available
Stepped concurrency: Ramps up through user-defined concurrency levels (default: 1 → 10 → 50 → 100 → 200 → 500)
Latency percentiles: Collects p50 / p90 / p99 latency at each level
Inflection point detection: Automatically identifies four types of performance inflection points
p99 latency accelerating (increase exceeds 2x the previous step's increase)
Throughput efficiency dropping significantly (RPS per connection drops > 40%)
Error rate surging (exceeds 1% and doubles from previous step)
Optimal concurrency recommendation: Automatically suggests the best concurrency level based on inflection points
Zero Python dependencies: Pure standard library implementation
Quick Start
# Basic usage — run default stepped load test against target URL
python3 scripts/http_benchmark.py https://example.com/api/health
# Custom concurrency steps and duration per step
python3 scripts/http_benchmark.py https://example.com/api/health -s 5,20,50,100,300 -d 15
# Specify ab as the engine
python3 scripts/http_benchmark.py https://example.com/ -t ab
# JSON-only output (for programmatic parsing)
python3 scripts/http_benchmark.py https://example.com/api/health --json
# Use ab with a specific number of requests per step
python3 scripts/http_benchmark.py https://example.com/ -t ab -n 5000
# Save JSON report to a file
python3 scripts/http_benchmark.py https://example.com/api/health --json > report.json