Peter Tschipper [ARCHIVE] on Nostr: 📅 Original date posted:2015-11-10 📝 Original message:On 10/11/2015 8:46 AM, ...

📅 Original date posted:2015-11-10
📝 Original message:On 10/11/2015 8:46 AM, Jeff Garzik via bitcoin-dev wrote:
> Comments:
>
> 1) cblock seems a reasonable way to extend the protocol. Further
> wrapping should probably be done at the stream level.
agreed.
>
> 2) zlib has crappy security track record.
>
Zlib had a bad buffer overflow bug but that was in 2005 and it got a lot
of press at the time. It's was fixed in version 1.2.3...we're on 1.2.8
now. I'm not aware of any other current issues with zlib. Do you have a
citation?

> 3) A fallback path to non-compressed is required, should compression
> fail or crash.
agreed.
>
> 4) Most blocks and transactions have runs of zeroes and/or highly
> common bit-patterns, which contributes to useful compression even at
> smaller sizes. Peter Ts's most recent numbers bear this out. zlib
> has a dictionary (32K?) which works well with repeated patterns such
> as those you see with concatenated runs of transactions.
>
> 5) LZO should provide much better compression, at a cost of CPU
> performance and using a less-reviewed, less-field-tested library.
I don't think LZO will give as good compression here but I will do some
benchmarking when I can.

>
>
>
>
>
> On Tue, Nov 10, 2015 at 11:30 AM, Tier Nolan via bitcoin-dev
> <bitcoin-dev at lists.linuxfoundation.org
> <mailto:bitcoin-dev at lists.linuxfoundation.org>> wrote:
>
>
>
> On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper
> <peter.tschipper at gmail.com <mailto:peter.tschipper at gmail.com>> wrote:
>
> There are better ways of sending new blocks, that's certainly
> true but for sending historical blocks and seding transactions
> I don't think so. This PR is really designed to save
> bandwidth and not intended to be a huge performance
> improvement in terms of time spent sending.
>
>
> If the main point is for historical data, then sticking to just
> blocks is the best plan.
>
> Since small blocks don't compress well, you could define a
> "cblocks" message that handles multiple blocks (just concatenate
> the block messages as payload before compression).
>
> The sending peer could combine blocks so that each cblock is
> compressing at least 10kB of block data (or whatever is optimal).
> It is probably worth specifying a maximum size for network buffer
> reasons (either 1MB or 1 block maximum).
>
> Similarly, transactions could be combined together and compressed
> "ctxs". The inv messages could be modified so that you can
> request groups of 10-20 transactions. That would depend on how
> much of an improvement compressed transactions would represent.
>
> More generally, you could define a message which is a compressed
> message holder. That is probably to complex to be worth the
> effort though.
>
>
>
>>
>> On Tue, Nov 10, 2015 at 5:40 AM, Johnathan Corgan via
>> bitcoin-dev <bitcoin-dev at lists.linuxfoundation.org
>> <mailto:bitcoin-dev at lists.linuxfoundation.org>> wrote:
>>
>> On Mon, Nov 9, 2015 at 5:58 PM, gladoscc via bitcoin-dev
>> <bitcoin-dev at lists.linuxfoundation.org
>> <mailto:bitcoin-dev at lists.linuxfoundation.org>> wrote:
>>
>>
>> I think 25% bandwidth savings is certainly
>> considerable, especially for people running full
>> nodes in countries like Australia where internet
>> bandwidth is lower and there are data caps.
>>
>>
>> ​ This reinforces the idea that such trade-off decisions
>> should be be local and negotiated between peers, not a
>> required feature of the network P2P.​
>>
>>
>> --
>> Johnathan Corgan
>> Corgan Labs - SDR Training and Development Services
>> http://corganlabs.com
>>
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>>
>>
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>
>
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