[chord] Analyze Chord in Planetlab?

[Emil Sit]

On Thu, 12 October 2006 at 23:27 (+0900), Hai Dao Le wrote:
> Now I am going to do my experiment on Chord. Do you (or anyone) know how
> can I analyze Chord? (e.g. calculate path length, stretch, ...).

I think if you send lsd a USR1 signal, it will dump a bunch
of stats to stderr that may include the average number of hops
(path length).  Unfortunately, it is not easy to extract
that from all the other junk that gets sent to stderr.
(Look for "Average # hops: [0-9.]+" perhaps.)

There isn't any code that calculates average stretch for you.
You'd have to define what you meant exactly (e.g., latencies
change over time) and add code that tries to figure it out.
You could at least time how long lookups take on average by
taking advantage of route_recchord's start_time variable
in route_recchord::handle_complete.

-- 
Emil Sit / MIT CSAIL PDOS / http://pdos.csail.mit.edu/chord/