[jrochkind1]

Mostly a reminder/clarification of things I knew, but a good and welcome one well-stated, because I probably sometimes forget. (I don't do performance work a lot).

But this:

> If you must use latency to measure efficiency, use mean (avg) latency. Yes, average latency

Not sure if I ever thought about it before, but after following the link[1] where OP talks more about it, they've convinced me. Definitely want mean latency at least in addition to median, not median alone.

[1]: https://brooker.co.za/blog/2017/12/28/mean.html

[marcosdumay]

> at least in addition to median

There was an interesting article here not long ago that made the point that median is basically useless. If you load 5 resources on a page load, the odds of all of them being faster than the median (so it represents the user experience) is about 3%. You need a very high rank to get any useful information, probably with a number of 9s.

[jrochkind1]

Median for a particular action/page might be more useful.

[marcosdumay]

No doubt about that (even then, you will probably want the 90 or 99 percentile, depending on how many interactions you expect a person to have).

Th real median is just very hard to measure, and an easier 99.99 (with more 9's as needed) rank is almost as good.

[jrochkind1]

Can you say more about why you say the "real median" is hard to measure? It doesn't seem hard to measure to me, or any harder than a 99.99 percentile. Why is 50th percentile harder to measure than 99.99th?

[zekrioca]

> If we're expecting 10 requests per second at peak this holiday season, we're good.

Problem is, sometimes system engineers do not know what to expect, but they still need to have a plan for this case.