[tor-dev] Scaling bandwidth scanner results

[teor]

Hi,

Matt, Juga, Nick and I discussed an alternative scaling scheme on
#tor-dev during the patch party.

> On 19 Mar 2018, at 12:22, Matt Traudt <pastly at torproject.org> wrote:
> 
> 1. Decide on a large total.
> 
> I suggest 50 million to start the conversation (bike shedding) based on
> that being close to the current total consensus weight so relay
> operators won't see a large (though inconsequential) change.

Calculate the average consensus weight per relay.
And make it a consensus parameter.
Currently, it's about 7500.

bwauths scale results so that the total measured bandwidth is
approximately 7500 * (the number of relays they have measured).

This scales their results so they are similar to the current torflow
bwauths. (The current bwauths have total measured bandwidths
between 35 million and 70 million. Using this scaling scheme, a
bwauth that measured 7000 relays would have a total bandwidth
of 52.5 million.)

This scheme also allows a bwauth to scale and report partial
results: if it has measured half the network, it scales to 25 million.

> 2. Have all the torflow operators switch to this new method.
> 
> Ouch. I wouldn't mind being told I'm wrong about this step being
> necessary.

Under this alternative scheme, if the unscaled bwauths average
relay weight changes, we change the consensus parameter.

So we don't need to change torflow.

See this pad for our notes and calculations:
https://pad.riseup.net/p/n3mEulClf6ZV

T
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