3 ms·
One of the first things I do at any job is replace the 90th percentile with the maximum in all plots. Really? I find percentiles to be more informative. Lookin
by lacker 5y ago
One of the first things I do at any job is replace the 90th percentile with the maximum in all plots.
Really? I find percentiles to be more informative. Looking at the maximum is like looking at an error log, it is basically throwing out all performance data except data from a tiny slice of time. A bad maximum shows you that a service failed at least once, but you oftenalready knew or expected that. A bad 90th percentile tells you that a lot of users are experiencing poor performance.
- loopz 5y agoWhen you care about it, use max. For enterprise, use 95 perc and charge 5x.
- kqr 5y agoWith fat tailed distributions, like the ones our latencies tend to look like, the signal is in the tail. The central/common observations are just noise and tell you little to nothing about how the system performs. That said, I do look at percentiles in addition to the max. But I find the 99th, 99.9th, and the max together tells me a lot more about the system performance than the uninformative stuff at the 90th and below.