[knot-dns-users] Estimating Knot's memory usage

Dear Knot developers, I'm testing Knot 1.3.0-rc1 now. One of the things I'd like to be able to do is to estimate Knot's memory usage without actually loading all my zones into it (because if it runs out of memory it will be killed). One very crude way was to load a single zone from a plain text zone file, and comparing the memory used by knot with the size of the zone on disk. For a zone of size 229MB, knot is using about 1.3GB of RAM. So I could say that knot wants about 6x as much RAM for each zone. Is this a reasonable asumption? Alternatively, since you know how knot uses memory for a zone, are you able to provide a small program which can read zones one at a time, calculate the RAM required for each zone, and then print a summary of the total RAM required to load all those zones into knot? We frequently get questions from our users along the lines of "I'd like you to slave this new zone" or "we are going to sign this zone; will your server be able to load it?" It would help an operator immensely if he can get an estimate of the additional RAM required. Regards, Anand Buddhdev RIPE NCC