Pretty much all your load generation and monitoring tools do not work correctly. Those charts you thought were full of relevant information about how your system is performing are really just telling you a lie. Your sensory inputs are being jammed.
To find out how listen to the Morpheous of performance monitoring Gil Tene, CTO and co-founder at Azul Systems, makers of truly high performance JVMs, in a mesmerizing talk on How NOT to Measure Latency.
This talk is about removing the wool from your eyes. It's the red pill option for what you thought you were testing with load generators.
If you want to hide the truth from someone show them a chart of all normal traffic with one just one bad spike surging into 95 percentile territory.
The number one indicator you should never get rid of is the maximum value. That’s not noise, it’s the signal, the rest is noise.
99% of users experience ~99.995%’ile response times, so why are you even looking at 95%'ile numbers?
Monitoring tools routinely drop important samples in the result set, leading you to draw really bad conclusions about the quality of the performance of your system.
It doesn't take long into the talk to realize Gil really knows his stuff. It's a deep talk with deep thoughts based on deep experience, filled with surprising insights. So if you take the red pill, you'll learn a lot, but you may not always like what you've learned.
Here's my inadequate gloss on Gil's amazing talk: