Indeed, monitoring of the maximum metric value (aka p100) is better than monitoring p99 or other percentiles:
- it shows the exact maximum without any approximations and errors;
- it is very easy and fast to calculate the maximum value among many maximum values obtained from
Ten years ago, I stopped using P99 and switched to P100, always.
- it’s easier to calculate (just take the max)
- it’s easier to understand (this is as bad as it gets, there’s nowhere to hide)
- optimizing for P100 tends to optimize for all percentiles (especially over time)
