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Amdahl's law: formula, examples and scaling limits
Amdahl's law explained with the formula, a speedup table and worked examples, plus Gustafson's law, the USL and what all three mean for load tests.
Concepts6 min read
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Queueing theory: what it is and why latency spikes
Queueing theory explained: arrivals, servers and Kendall's notation, why response time climbs sharply near full utilization, and what that means for tests.
Concepts6 min read
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SLO vs SLA: the difference, SLIs and error budgets
SLO vs SLA explained: who sets each, what an SLI is, how error budgets work, the downtime 99.9% allows, and how to check an SLO with a load test.
Concepts7 min read
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Apdex score: what it is and how to calculate it
Apdex score explained: the formula, how to choose the T threshold, a worked example, and how JMeter, Artillery and LoadFocus compute it in a load test.
Concepts7 min read
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Tail latency: what it is and how to measure it
Tail latency explained: why the slowest 1% of requests matters, how fan-out makes it worse, what causes it, and how to measure p99 honestly in a load test.
Concepts7 min read
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Throughput vs latency: how they interact under load
Throughput vs latency explained: what each measures, why JMeter's Latency is not response time, and why latency climbs once throughput hits a ceiling.
Concepts7 min read
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Coordinated omission: what it is and how to avoid it
Coordinated omission explained: why a load generator that waits for slow replies hides them, how to spot it and how wrk2, k6, Gatling and JMeter avoid it.
Concepts7 min read
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Little's law in load testing: size and check your tests
Little's law in load testing explained: how users, request rate and response time fit together, how to size a closed-model test, and where it breaks.
Concepts7 min read
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Open vs closed workload model: which one should you use?
Open vs closed workload model explained: arrival rate or fixed users, why closed tests hide slowdowns, and how k6, Gatling, Locust and JMeter model each.
Concepts7 min read
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Think time in load testing: what it is and how to set it
Think time in load testing explained: why pauses change the load your users create, think time vs pacing, and how to set it in k6, JMeter and Locust.
Concepts7 min read
