- From: Martin Thomson <martin.thomson@gmail.com>
- Date: Mon, 18 Jul 2016 15:27:54 +0200
- To: HTTP Working Group <ietf-http-wg@w3.org>

The draft describes how to select P to achieve a particular false positive probability. The net effect of this is that you get approximately the probability. I think that this would be better if there was a description of how to decide on an upper bound for the false positive probability. The calculation is a little less clean: n is the number of resources p is the lower bound of the probability of false positive P is the number of fixed bits allocated to each entry N+P is the width of the hash output All of these are integers, except p, which is a number between 0 and 1. The current draft chooses: P = ??(0 - log2(p)) - it's not clear, but I imagine that this uses floor() N = round(log2(n)) I propose that we instead do: P = round(0 - log2(p)) N+P = ceil(log2(n)-log2(p)) This is, I think, a much better calculation. We would still benefit from encoding N and P separately.

Received on Monday, 18 July 2016 13:28:33 UTC