Are you doing more testing?

On Saturday 13 June 2009 19:05:36 Evan Daniel wrote:
> On Sat, Jun 13, 2009 at 1:08 PM, Matthew
> Toseland<toad at amphibian.dyndns.org> wrote:
> > Now that 0.7.5 has shipped, we can start making disruptive changes again in 
> > a few days. The number one item on freenet.uservoice.com has been for some 
> > time to allow more opennet peers for fast nodes. We have discussed this in 
> > the past, and the conclusions which I agree with and some others do:
> > - This is feasible.
> > - It will not seriously break routing.
> > - Reducing the number of connections on slow nodes may actually be a gain 
> > in security, by increasing opportunities for coalescing. It will improve 
> > payload percentages, improve average transfer rates, let slow nodes accept 
> > more requests from each connection, and should improve overall performance.
> > - The network should be less impacted by the speed of the slower nodes.
> > - But we have tested using fewer connections on slow nodes in the past and 
> > had anecdotal evidence that it is slower. We need to evaluate it more 
> > rigorously somehow.
> > - Increasing the number of peers allowed for fast opennet nodes, within 
> > reason, should not have a severe security impact. It should improve routing 
> > (by a smaller network diameter). It will of course allow fast nodes to 
> > contribute more to the network. We do need to be careful to avoid 
> > overreliance on ubernodes (hence an upper limit of maybe 50 peers).
> > - Routing security: FOAF routing allows you to capture most of the traffic 
> > from a node already, the only thing stopping this is the 30%-to-one-peer 
> > limit.
> > - Coalescing security: Increasing the number of peers without increasing 
> > the bandwidth usage does increase vulnerability to traffic analysis by 
> > doing less coalescing. On the other hand, this is not a problem if the 
> > bandwidth usage scales with the number of nodes.
> >
> > How can we move forward? We need some reliable test results on whether a 
> > 10KB/sec node is better off with 10 peers or with 20 peers. I think it's a 
> > fair assumption for faster nodes. Suggestions?
> 
> I haven't tested at numbers that low.  At 15KiB/s, the stats page
> suggests your slightly better off with 12-15 peers than 20.  I saw no
> subjective difference in browsing speed either way.
> 
> I'm happy to do some testing here, if you tell me what data you want
> me to collect.  More testers would obviously be good.
> 
> >
> > We also need to set some arbitrary parameters. There is an argument for 
> > linearity, to avoid penalising nodes with different bandwidth levels, but 
> > nodes with more peers and the same amount of bandwidth per peer are likely 
> > to be favoured by opennet anyway... Non-linearity, in the sense of having a 
> > lower threshold and an upper threshold and linearly add peers between them 
> > but not necessarily consistently with the lower threshold, would mean fewer 
> > nodes with lots of peers, and might achieve better results? E.g.
> >
> > 10 peers at 10KB/sec ... 20 peers at 20KB/sec (1 per KB/sec)
> > 20 peers at 20KB/sec ... 50 peers at 80KB/sec (1 per 3KB/sec)
> 
> I wouldn't go as low as 10 peers, simply because I haven't tested it.
> Other than that, those seem perfectly sensible to me.
> 
> We should also watch for excessive cpu usage.  If there's lots of bw
> available, we'd want to have just enough connections to not quite
> limit on available cpu power.  Of course, I don't really know how many
> connections / how much bw it is before that becomes a concern.
> 
> Evan Daniel
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