[tor-relays] Relay accounting calculations

[Steve Snyder]

I'm not sure I understand how the relay accounting limit is calculated.

The manual says that you might specify an AccountingMax limit of 1 GB, a ceiling that would be applied to each of the input and output traffic.  The manual also says that it is known the output traffic can be larger than the input traffic, especially if you're running an exit node.  (I imagine that the converse applies if you also have Tor clients on the same network, using the node, though the manual doesn't say so.)

Given that the AccountingMax value applies to traffic in each direction, one would have to specify a rate that is half their actual limit.  That is, given a 100GB limit one would specify "AccountingMax 50 GB" in the config file, causing the relay to sleep when 50GB is reached in either input or output traffic.

Is the algorithm really this inflexible?  If I reach 50GB on output traffic, with only 49GB of input traffic, that puts the relay into hibernation with 1GB of bandwidth left unused.

That seems counter-intuitive to me.  Is the manual inaccurate, or am I just missing the hidden genius of tracking input and output traffic as distinct pools?  It seems more sensible to specify the full bandwidth allotment, with the relay hibernating when the sum of the input and output traffic reach that limit.