Average latency up 50ms but p99 flat: diagnose the discrepancy
Tests if you know mean reflects full distribution while p99 is a threshold. Strong answers hypothesize body shift like cache misses or traffic mix changes, and demand histograms and segmentation by endpoint. Red flag: blaming outliers, which would raise p99.
Tests whether you understand that mean reflects the entire distribution while p99 is only a threshold. A strong answer hypothesizes the latency increase lives in the body, not the tail. Examples include a drop in cache hit rate, a new moderately slow endpoint gaining volume, or fixed overhead added to common paths. It then calls for histograms and CDFs to see where the mass shifted, plus segmentation by endpoint, region, deployment, and payload size. Red flag: blaming outliers or suggesting that p99 is somehow averaged into the mean.
Read the original → aerospike.com
- #latency
- #percentiles
- #metrics
- #debugging
- #distributions
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