Proposal 167: Vote on network parameters in consensus

[Nick Mathewson]

On Tue, Aug 25, 2009 at 12:32:06AM -0400, Roger Dingledine wrote:
> Filename: 167-params-in-consensus.txt
> Title: Vote on network parameters in consensus
> Author: Roger Dingledine
> Created: 18-Aug-2009
> Status: Open
> Target: 0.2.2
> 
> 0. History
> 
> 
> 1. Overview
> 
>   Several of our new performance plans involve guessing how to tune
>   clients and relays, yet we won't be able to learn whether we guessed
>   the right tuning parameters until many people have upgraded. Instead,
>   we should have directory authorities vote on the parameters, and teach
>   Tors to read the currently recommended values out of the consensus.
> 
> 2. Design
> 
>   V3 votes should include a new "params" line after the known-flags
>   line. It contains key=value pairs, where value is an integer.

Let's say that all the keys need to match the Keyword pattern in
dir-spec.txt.
 
>   Consensus documents that are generated with a sufficiently new consensus
>   method (7?) then include a params line that includes every key listed
>   in any vote,

We need to specify what order the parameters appear in the consensus,
and what position in the consensus the parameters line appears.  Let's
say that the keys are sorted lexically in the output, and that the
line appears directly after "known-flags".

> and the median value for that key (in case of ties,
>   we use the median closer to zero).

Is +1 or -1 closer to zero? ;)

For the sake of our sanity, why not have it be "the lower median"?
That's easiest to implement.

Note that the design here allows any authority to introduce an
arbitrary number of parameters.

yrs,
-- 
Nick