On Wed, Nov 26, 2003 at 01:00:26AM -0500, Ken Corson wrote: > Toad wrote: > >Hypothetical: > >Routing works, so we have a 20% success ratio. > >The average filesize is 200kB (this is about right on the current > >network, check your datastore - but maybe we need to gather more > >accurate stats on it). > >We have a 256kbps uplink i.e. 32kB/sec, of which we can use all (this is > >optimistic). > >We get a mere 10kqph incoming, and accept all of it. > > > >I will now demonstrate that this is impossible: > >10kqph * 0.2 = 2kqph. > >2000 * 200kB = 409,600,000 bytes > >409,600,000 bytes / 3600 seconds = 113,777 bytes per second, for > >trailers alone, assuming no connection and search overhead. > > > >Ideas? > > this is based in pure reality :) as a practical matter, the times at > which trailers will be created obeys a Poisson distribution. This > is basic queueing theory in a nutshell. It is becoming clear that > a certain bandwidth capacity will determine an optimal qph for any > given node. We cannot control the success rate of queries, however, > it should average out over some period of time. We seem to have > acknowledged that we cannot accept as many queries once we become > burdened (or blessed really) with "too many" trailers. This is the > balance we seek between query traffic and trailer traffic. We can > prioritize between trailers by dedicating more, or less, bandwidth > to individual transfers. The goal is to service each one "fairly," > while attempting to maintain a relatively constant number of active > trailers over time. > > My hat is off to Toad for identifying hard limits that we simply will > never go beyond! It frames the overall problem quite concisely. I > suspect these variables could also help to produce a more meaningful > or accurate %load factor. > > There is an obvious inverse relationship between (average) individual > trailer transfer rates and the number of active trailers... many slow > or few that are fast - take your choice. But the first step is to > approximate the optimum qph for a node with a given bandwidth.
Can we even do that? We don't know the success ratio, which may well be a function of load anyway! > > -Ken -- Matthew J Toseland - [EMAIL PROTECTED] Freenet Project Official Codemonkey - http://freenetproject.org/ ICTHUS - Nothing is impossible. Our Boss says so.
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