📅 Original date posted:2015-11-11
📝 Original message:If that were true then we wouldn't need to gzip large files before
sending them over the internet. Data compression generally helps
transmission speed as long as the amount of compression is high enough
and the time it takes is low enough to make it worthwhile. On a
corporate LAN it's generally not worthwhile unless you're dealing with
very large files, but over a corporate WAN or the internet where network
latency can be high it is IMO a worthwhile endevor.
On 11/11/2015 10:49 AM, Marco Pontello wrote:
> A random thought: aren't most communication over a data link already
> compressed, at some point?
> When I used a modem, we had the V.42bis protocol. Now, nearly all ADSL
> connections using PPPoE, surely are. And so on.
> I'm not sure another level of generic, data agnostic kind of
> compression will really give us some real-life practical advantage
> over that.
>
> Something that could take advantage of of special knowledge of the
> specific data, instead, would be an entirely different matter.
>
> Just my 2c.
>
> On Wed, Nov 11, 2015 at 7:35 PM, Peter Tschipper via bitcoin-dev
> <bitcoin-dev at lists.linuxfoundation.org
> <mailto:bitcoin-dev at lists.linuxfoundation.org>> wrote:
>
> Here are the latest results on compression ratios for the first
> 295,000 blocks, compressionlevel=6. I think there are more than
> enough datapoints for statistical significance.
>
> Results are very much similar to the previous test. I'll work on
> getting a comparison between how much time savings/loss in time
> there is when syncing the blockchains: compressed vs
> uncompressed. Still, I think it's clear that serving up
> compressed blocks, at least historical blocks, will be of benefit
> for those that have bandwidth caps on their internet connections.
>
> The proposal, so far is fairly simple:
> 1) compress blocks with some compression library: currently zlib
> but I can investigate other possiblities
> 2) As a fall back we need to advertise compression as a service.
> That way we can turn off compression AND decompression completely
> if needed.
> 3) Do the compression at the datastream level in the code.
> CDataStream is the obvious place.
>
>
> Test Results:
>
> range = block size range
> ubytes = average size of uncompressed blocks
> cbytes = average size of compressed blocks
> ctime = average time to compress
> dtime = average time to decompress
> cmp_ratio% = compression ratio
> datapoints = number of datapoints taken
>
> range ubytes cbytes ctime dtime cmp_ratio%
> datapoints
> 0-250b 215 189 0.001 0.000 12.40
> 91280
> 250-500b 438 404 0.001 0.000 7.85
> 13217
> 500-1KB 761 701 0.001 0.000
> 7.86 11434
> 1KB-10KB 4149 3547 0.001 0.000 14.51
> 52180
> 10KB-100KB 41934 32604 0.005 0.001 22.25 82890
> 100KB-200KB 146303 108080 0.016 0.001 26.13 29886
> 200KB-300KB 243299 179281 0.025 0.002 26.31 25066
> 300KB-400KB 344636 266177 0.036 0.003 22.77 4956
> 400KB-500KB 463201 356862 0.046 0.004 22.96 3167
> 500KB-600KB 545123 429854 0.056 0.005 21.15 366
> 600KB-700KB 647736 510931 0.065 0.006 21.12 254
> 700KB-800KB 746540 587287 0.073 0.008 21.33 294
> 800KB-900KB 868121 682650 0.087 0.008 21.36 199
> 900KB-1MB 945747 726307 0.091 0.010 23.20 304
>
> 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.
>>
>> 2) zlib has crappy security track record.
>>
>> 3) A fallback path to non-compressed is required, should
>> compression fail or crash.
>>
>> 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.
>>
>>
>>
>>
>>
>> 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
>>>
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev at lists.linuxfoundation.org
>>> <mailto:bitcoin-dev at lists.linuxfoundation.org>
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> bitcoin-dev mailing list
>>> bitcoin-dev at lists.linuxfoundation.org
>>> <mailto:bitcoin-dev at lists.linuxfoundation.org>
>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev at lists.linuxfoundation.org
>> <mailto:bitcoin-dev at lists.linuxfoundation.org>
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>
>>
>>
>>
>> _______________________________________________
>> bitcoin-dev mailing list
>> bitcoin-dev at lists.linuxfoundation.org
>> <mailto:bitcoin-dev at lists.linuxfoundation.org>
>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev at lists.linuxfoundation.org
> <mailto:bitcoin-dev at lists.linuxfoundation.org>
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>
>
>
> --
> Try the Online TrID File Identifier
> http://mark0.net/onlinetrid.aspx
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Peter Tschipper [ARCHIVE] /
npub14s…653tk
2023-06-07 17:44:26
in reply to nevent1q…njhe
Author Public Key
npub14sxt5nq5l8hfvd7yfcmh8gwjqhtzcc72vz2lcwd2uw0xlllwdayqk653tkPublished at
2023-06-07 17:44:26Event JSON
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"content": "📅 Original date posted:2015-11-11\n📝 Original message:If that were true then we wouldn't need to gzip large files before\nsending them over the internet. Data compression generally helps\ntransmission speed as long as the amount of compression is high enough\nand the time it takes is low enough to make it worthwhile. On a\ncorporate LAN it's generally not worthwhile unless you're dealing with\nvery large files, but over a corporate WAN or the internet where network\nlatency can be high it is IMO a worthwhile endevor.\n\n\n\nOn 11/11/2015 10:49 AM, Marco Pontello wrote:\n\u003e A random thought: aren't most communication over a data link already\n\u003e compressed, at some point?\n\u003e When I used a modem, we had the V.42bis protocol. Now, nearly all ADSL\n\u003e connections using PPPoE, surely are. And so on.\n\u003e I'm not sure another level of generic, data agnostic kind of\n\u003e compression will really give us some real-life practical advantage\n\u003e over that.\n\u003e\n\u003e Something that could take advantage of of special knowledge of the\n\u003e specific data, instead, would be an entirely different matter.\n\u003e\n\u003e Just my 2c.\n\u003e\n\u003e On Wed, Nov 11, 2015 at 7:35 PM, Peter Tschipper via bitcoin-dev\n\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\n\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\u003e wrote:\n\u003e\n\u003e Here are the latest results on compression ratios for the first\n\u003e 295,000 blocks, compressionlevel=6. I think there are more than\n\u003e enough datapoints for statistical significance. \n\u003e\n\u003e Results are very much similar to the previous test. I'll work on\n\u003e getting a comparison between how much time savings/loss in time\n\u003e there is when syncing the blockchains: compressed vs\n\u003e uncompressed. Still, I think it's clear that serving up\n\u003e compressed blocks, at least historical blocks, will be of benefit\n\u003e for those that have bandwidth caps on their internet connections.\n\u003e\n\u003e The proposal, so far is fairly simple:\n\u003e 1) compress blocks with some compression library: currently zlib\n\u003e but I can investigate other possiblities\n\u003e 2) As a fall back we need to advertise compression as a service. \n\u003e That way we can turn off compression AND decompression completely\n\u003e if needed.\n\u003e 3) Do the compression at the datastream level in the code. \n\u003e CDataStream is the obvious place.\n\u003e\n\u003e\n\u003e Test Results:\n\u003e\n\u003e range = block size range\n\u003e ubytes = average size of uncompressed blocks\n\u003e cbytes = average size of compressed blocks\n\u003e ctime = average time to compress\n\u003e dtime = average time to decompress\n\u003e cmp_ratio% = compression ratio\n\u003e datapoints = number of datapoints taken\n\u003e\n\u003e range ubytes cbytes ctime dtime cmp_ratio% \n\u003e datapoints\n\u003e 0-250b 215 189 0.001 0.000 12.40 \n\u003e 91280\n\u003e 250-500b 438 404 0.001 0.000 7.85 \n\u003e 13217\n\u003e 500-1KB 761 701 0.001 0.000 \n\u003e 7.86 11434\n\u003e 1KB-10KB 4149 3547 0.001 0.000 14.51 \n\u003e 52180\n\u003e 10KB-100KB 41934 32604 0.005 0.001 22.25 82890\n\u003e 100KB-200KB 146303 108080 0.016 0.001 26.13 29886\n\u003e 200KB-300KB 243299 179281 0.025 0.002 26.31 25066\n\u003e 300KB-400KB 344636 266177 0.036 0.003 22.77 4956\n\u003e 400KB-500KB 463201 356862 0.046 0.004 22.96 3167\n\u003e 500KB-600KB 545123 429854 0.056 0.005 21.15 366\n\u003e 600KB-700KB 647736 510931 0.065 0.006 21.12 254\n\u003e 700KB-800KB 746540 587287 0.073 0.008 21.33 294\n\u003e 800KB-900KB 868121 682650 0.087 0.008 21.36 199\n\u003e 900KB-1MB 945747 726307 0.091 0.010 23.20 304\n\u003e\n\u003e On 10/11/2015 8:46 AM, Jeff Garzik via bitcoin-dev wrote:\n\u003e\u003e Comments:\n\u003e\u003e\n\u003e\u003e 1) cblock seems a reasonable way to extend the protocol. Further\n\u003e\u003e wrapping should probably be done at the stream level.\n\u003e\u003e\n\u003e\u003e 2) zlib has crappy security track record.\n\u003e\u003e\n\u003e\u003e 3) A fallback path to non-compressed is required, should\n\u003e\u003e compression fail or crash.\n\u003e\u003e\n\u003e\u003e 4) Most blocks and transactions have runs of zeroes and/or highly\n\u003e\u003e common bit-patterns, which contributes to useful compression even\n\u003e\u003e at smaller sizes. Peter Ts's most recent numbers bear this out.\n\u003e\u003e zlib has a dictionary (32K?) which works well with repeated\n\u003e\u003e patterns such as those you see with concatenated runs of\n\u003e\u003e transactions.\n\u003e\u003e\n\u003e\u003e 5) LZO should provide much better compression, at a cost of CPU\n\u003e\u003e performance and using a less-reviewed, less-field-tested library.\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e On Tue, Nov 10, 2015 at 11:30 AM, Tier Nolan via bitcoin-dev\n\u003e\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\u003e wrote:\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper\n\u003e\u003e \u003cpeter.tschipper at gmail.com\n\u003e\u003e \u003cmailto:peter.tschipper at gmail.com\u003e\u003e wrote:\n\u003e\u003e\n\u003e\u003e There are better ways of sending new blocks, that's\n\u003e\u003e certainly true but for sending historical blocks and\n\u003e\u003e seding transactions I don't think so. This PR is really\n\u003e\u003e designed to save bandwidth and not intended to be a huge\n\u003e\u003e performance improvement in terms of time spent sending.\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e If the main point is for historical data, then sticking to\n\u003e\u003e just blocks is the best plan.\n\u003e\u003e\n\u003e\u003e Since small blocks don't compress well, you could define a\n\u003e\u003e \"cblocks\" message that handles multiple blocks (just\n\u003e\u003e concatenate the block messages as payload before compression). \n\u003e\u003e\n\u003e\u003e The sending peer could combine blocks so that each cblock is\n\u003e\u003e compressing at least 10kB of block data (or whatever is\n\u003e\u003e optimal). It is probably worth specifying a maximum size for\n\u003e\u003e network buffer reasons (either 1MB or 1 block maximum).\n\u003e\u003e\n\u003e\u003e Similarly, transactions could be combined together and\n\u003e\u003e compressed \"ctxs\". The inv messages could be modified so\n\u003e\u003e that you can request groups of 10-20 transactions. That\n\u003e\u003e would depend on how much of an improvement compressed\n\u003e\u003e transactions would represent.\n\u003e\u003e\n\u003e\u003e More generally, you could define a message which is a\n\u003e\u003e compressed message holder. That is probably to complex to be\n\u003e\u003e worth the effort though.\n\u003e\u003e\n\u003e\u003e \n\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e On Tue, Nov 10, 2015 at 5:40 AM, Johnathan Corgan via\n\u003e\u003e\u003e bitcoin-dev \u003cbitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\u003e wrote:\n\u003e\u003e\u003e\n\u003e\u003e\u003e On Mon, Nov 9, 2015 at 5:58 PM, gladoscc via\n\u003e\u003e\u003e bitcoin-dev \u003cbitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\u003e wrote:\n\u003e\u003e\u003e \n\u003e\u003e\u003e\n\u003e\u003e\u003e I think 25% bandwidth savings is certainly\n\u003e\u003e\u003e considerable, especially for people running full\n\u003e\u003e\u003e nodes in countries like Australia where internet\n\u003e\u003e\u003e bandwidth is lower and there are data caps.\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e This reinforces the idea that such trade-off\n\u003e\u003e\u003e decisions should be be local and negotiated between\n\u003e\u003e\u003e peers, not a required feature of the network P2P.\n\u003e\u003e\u003e \n\u003e\u003e\u003e\n\u003e\u003e\u003e -- \n\u003e\u003e\u003e Johnathan Corgan\n\u003e\u003e\u003e Corgan Labs - SDR Training and Development Services\n\u003e\u003e\u003e http://corganlabs.com\n\u003e\u003e\u003e\n\u003e\u003e\u003e _______________________________________________\n\u003e\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e _______________________________________________\n\u003e\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e _______________________________________________\n\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e \u003cmailto:bitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n\u003e\n\u003e\n\u003e\n\u003e -- \n\u003e Try the Online TrID File Identifier\n\u003e http://mark0.net/onlinetrid.aspx\n\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151111/89fce255/attachment-0001.html\u003e",
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