On Sat, Oct 08, 2005 at 08:12:11AM +0300, Edgar Friendly wrote: > Matthew Toseland wrote: > >According to the docs, decoding cannot begin until we have a full > >segment. So the opportunities for progressive decoding are limited, but > >we can use 4MB segments and decode one segment while fetching the next. > >This should provide significantly improved performance relative to what > >we do now, at a higher CPU cost. Small files *should* decode in a very > >few seconds even on slow CPUs with the pure java code. > > Switching to 4MB segments will also cut the effectiveness of the FEC, as > each block will check for fewer other blocks.
No, it won't. 4MB = 32kB * 128. Same number. We could cut it to 1MB segments for a MAJOR gain in CPU performance, but that WOULD cut the FEC effectiveness significantly. Justin tells me that most users of onion FEC use a 32/something FEC; 128/192 is huge. > To be honest, the > effectiveness of the FEC probably isn't a weakness as 50% redundancy is > a lot of margin for error. > > I wish we/I could talk with a patent lawyer about the tornado codes > patent. There's no way they can be patenting the idea of XORing data > blocks together to produce check blocks, can they? They've got to be > patenting some other ideas, like the cascading of their FEC and the > method of choosing what blocks to XOR. These are important for the > purposes they use tornado codes for, but freenet should[1] be nearly > immune to these requirements because of the fact that the client gets to > choose what blocks to request, instead of having the server just > broadcast information. I haven't seen any evidence of LDPC codes which are not covered by one or other patent... I can see some practical reasons to use onion, but I could be persuaded to use something else - IF the only patents on it are completely trivial ones. > > Anyway, I'm back in a little way for the moment. I'm still working on > re-implementing the node in ocaml, probably using the mldonkey project's > codebase as at least a huge library of p2p networking code. It's good that you are back. Have you seen the 0.7 branch? We have changed an awful lot of things... (including from CVS to SVN). > > Thelema -- Matthew J Toseland - toad at amphibian.dyndns.org Freenet Project Official Codemonkey - http://freenetproject.org/ ICTHUS - Nothing is impossible. Our Boss says so. -------------- next part -------------- A non-text attachment was scrubbed... Name: signature.asc Type: application/pgp-signature Size: 189 bytes Desc: Digital signature URL: <https://emu.freenetproject.org/pipermail/tech/attachments/20051103/57f2a8e4/attachment.pgp>
