2 ms·
> People who are bad at statistics. Heh! sadly very true. Many of those who do care about the p95s of an internal service often do it with a sense of chivalry
by srean 8y ago
> People who are bad at statistics.
Heh! sadly very true.
Many of those who do care about the p95s of an internal service often do it with a sense of chivalry that they have that 5% of the users back. The end user latency percentiles would be quite different from the service side latency, more so if its composed by a "Last_of" or a Max operator.
At times I feel tempted to write a library that offers primitives to glue microservice calls such as fan_out, retry, timeout etc but one that can reason about the percentiles of the output from the percentiles of the input.
BTW are statistical properties of latencies covered in distributed system courses ? I thought they were mostly about different kinds of guarantees, such as consensus, atleast-once, atmost-once etc etc.
- hinkley 8y agoHeck no, I got a little bit in a multivariate stats class but the rest I had to pick up in the field or a bit from books. I had a particularly illuminating moment with my ops guy trying to work out how often we could expect a drive to fail in a ten drive array and it was pretty shocking. My knowledge is pretty thin, but the fact that I even know what questions to ask puts me in a better spot to contribute than 4 out of 5 people in the room. That shouldn’t be how things are, but that’s where we are. Every new (old) technique is a bunch of naive people crossing their fingers and hoping things go better than last time.
- srean 8y agoI thought as much. Your handle has anything to do with https://books.google.co.in/books/about/Theoretical_Statistics.html?id=ppoujo-BInsC https://books.google.co.in/books/about/Theoretical_Statistic... ? very nice book BTW