On Mon, Jul 26, 2004 at 03:32:08PM -0700, Ken Bloom wrote: > Hi, Pete, > My research project this summer concerns BitTorrent. (Although I'm > currently working on the choking algorithm, not the piece selection > algorithm.) What program is giving you the display right now? Is it a > client, or a tracker on the web? I don't see the string "distributed" > anywhere in Bram Cohen's 3.4.2 sources.
The wording of "distributed copies" was originally added by ChocoEd's statistics patch (http://www.edkeyes.org/btstats.html) to Bram's official client. The number of distributed copies is generally shown in your client, and only counts the peers (usually not counting seeds)[0] you are connected to. I don't believe I've ever seen a tracker show the distributed copies. > What I do observe is that the Knoppix BitTorrent site > (http://torrent.unix-ag.uni-kl.de:6969/) displays average progress for > its downloads. Average progress there is currently 29% on the english > downloads, reporting 62 seeds and 12 "leechers" (who are downloading > and uploading - because the tracker has no clue if a peer isn't > uploading). Obviously if the seeds were included in this "average" > then this number would have to be higher than 50%, so I think that > this tracker averages across the peers that don't have the complete > file yet. Is it possible that "distributed copies" means "average > progress"? Nope. Average copies (sometimes seend as XX.X% done/downloaded) is just pretty much what you said. Add up the percentage complete of all the peers, and divide by the number of peers. Going back to Samuel's 5 part file example (slightly modified): Alice 1 2 3 4 Bob 1 3 4 Carol 2 3 (nobody has piece 5) Our average copies is (80% + 60% + 40%)/3 or 60%, but our distributed copies is 0.80 (or 80%) because we can make 0.8 complete copies with what is out there. If Carol suddenly gets piece 5 (from some unknown seed) our average copies goes to (80% + 60% + 60%)/3 or 66%, but your distributed copies goes to 1.80 (Alice's 4 pieces and Carol's piece 5 make 1. Bob's 3 and Carol's piece 2 make the .8. Carol's last piece is not counted.) [0] Some clients will include seeds in this count, but will usually name it something different, like "Available copies" _______________________________________________ vox-tech mailing list [EMAIL PROTECTED] http://lists.lugod.org/mailman/listinfo/vox-tech
