[bittorrent] State of Super-seeding

bittorrent-list.funchords at dfgh.net bittorrent-list.funchords at dfgh.net
Thu Aug 9 12:42:40 EDT 2007

On 8/9/07, tiennou <tiennou7 at gmail.com> wrote:
> - Is it really useful to implement Superseeding ? (There's a post in the
> archives saying that the updated choke algorithm was now sufficient.)

It is useful to implement Super-Seeding.  I typically shave 20-25% off the
time and bytes it takes to sufficiently seed a swarm over the standard choke

- The spec says that I should "masquerade as a normal client with no data",
> but I'm at a loss with what to do about the tracker ?
> Right now I'm thinking :
> * Tell tracker I have no data

No, tell the tracker you are a seeder.  There will be no difference between
the tracker message you send as a seeder vs. as a super-seeder.

* Process tracker data to know if I can super-seed

That's a thought.

When Super-Seeding is active, Azureus starts in Super-Seeding mode, starting
from piece 0 and delivering only pieces unique to the swarm.  When Azureus
reaches the final piece, or encounters another seeder, then it switches from
Super-Seeding mode to Seeding mode.  Azureus will not switch from
downloading to Super-Seeding.

uTorrent seems to stay in Super-Seeding mode (they call it Initial Seeding),
delivering the rarest pieces.  When set, it does not seem to ever drop out
of that mode.

Both methods, though very different, seem to deliver similar improved
performance for the first seeder.  I'll say more below.

* If I can't super-seed, re-tell tracker I have the data (but isn't that
> hammering ?)

N/A (see the answer above -- you'll tell the tracker that you're a seeder)

- Superseeding can be used at anytime, right ? The only thing is that I
> should be the only seed.

John Hoffman suggests that it be used for low speed, low number of slots,
first seeders only.

My experience is that the speed and slots doesn't matter.  The performance
improvement scales across lower and higher speeds.

uTorrent has taken this question even further, giving users the option to
always Super-Seed.  To me, users that choose to do that stretch the purpose
somewhat (too much) further than intended, since it takes piece selection
out of the hands of the peers and is unnecessary when holding no unique
pieces. But the idea of "let the users decide" has not caused wide-spread
abuse of the feature, IMHO, and may be a way for you to go.

Good questions... I hope this helps.
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