[tor-dev] Statistics on fraction of connections used uni-/bidirectionally

[Karsten Loesing]

Björn, Florian,

a few years back (in 2010, to be precise) we added statistics to
little-t-tor reporting what fraction of connections is used
uni-/bidirectionally.  Quoting dir-spec.txt:

"conn-bi-direct" YYYY-MM-DD HH:MM:SS (NSEC s) BELOW,READ,WRITE,BOTH NL
    [At most once]

    Number of connections, split into 10-second intervals, that are
    used uni-directionally or bi-directionally as observed in the NSEC
    seconds (usually 86400 seconds) before YYYY-MM-DD HH:MM:SS.  Every
    10 seconds, we determine for every connection whether we read and
    wrote less than a threshold of 20 KiB (BELOW), read at least 10
    times more than we wrote (READ), wrote at least 10 times more than
    we read (WRITE), or read and wrote more than the threshold, but
    not 10 times more in either direction (BOTH).  After classifying a
    connection, read and write counters are reset for the next
    10-second interval.

These statistics are disabled by default, but when they are enabled,
relays publish them in their extra-info descriptors.  And quite a few
relays do that.  Here's a (bad) visualization (that used to be slightly
less bad when fewer relays published these statistics):

https://metrics.torproject.org/performance.html#connbidirect

Here's the question: Is there still value in having these statistics?  I
recall that they were useful in 2010, but will that still be the case in
2013?

If the answer is "yes", never mind.

If the answer is "no", I'd create a ticket and submit a patch to remove
code parts from little-t-tor, and I'd remove the not-really-useful graph
from the metrics website.

Cc'ing Rob, Aaron, and Roger as the people who typically have an
interest in these kinds of statistics.  If other tor-dev@ people have an
opinion on this, please raise your voice!

All the best,
Karsten