š
Original date posted:2015-11-11
š Original message: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.
>>
>>
>> ā 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.ā
>>
>>
>> --
>> 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
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
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Peter Tschipper [ARCHIVE] /
npub14sā¦653tk
2023-06-07 17:44:24
in reply to nevent1qā¦89vx
Author Public Key
npub14sxt5nq5l8hfvd7yfcmh8gwjqhtzcc72vz2lcwd2uw0xlllwdayqk653tkSeen on
wss://relay.noswhere.comPublished at
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"content": "š
Original date posted:2015-11-11\nš Original message:Here are the latest results on compression ratios for the first 295,000\nblocks, compressionlevel=6. I think there are more than enough\ndatapoints for statistical significance. \n\nResults are very much similar to the previous test. I'll work on\ngetting a comparison between how much time savings/loss in time there is\nwhen syncing the blockchains: compressed vs uncompressed. Still, I\nthink it's clear that serving up compressed blocks, at least historical\nblocks, will be of benefit for those that have bandwidth caps on their\ninternet connections.\n\nThe proposal, so far is fairly simple:\n1) compress blocks with some compression library: currently zlib but I\ncan investigate other possiblities\n2) As a fall back we need to advertise compression as a service. That\nway we can turn off compression AND decompression completely if needed.\n3) Do the compression at the datastream level in the code. CDataStream\nis the obvious place.\n\n\nTest Results:\n\nrange = block size range\nubytes = average size of uncompressed blocks\ncbytes = average size of compressed blocks\nctime = average time to compress\ndtime = average time to decompress\ncmp_ratio% = compression ratio\ndatapoints = number of datapoints taken\n\nrange ubytes cbytes ctime dtime cmp_ratio% datapoints\n0-250b 215 189 0.001 0.000 12.40 91280\n250-500b 438 404 0.001 0.000 7.85 13217\n500-1KB 761 701 0.001 0.000 7.86 11434\n1KB-10KB 4149 3547 0.001 0.000 14.51 52180\n10KB-100KB 41934 32604 0.005 0.001 22.25 82890\n100KB-200KB 146303 108080 0.016 0.001 26.13 29886\n200KB-300KB 243299 179281 0.025 0.002 26.31 25066\n300KB-400KB 344636 266177 0.036 0.003 22.77 4956\n400KB-500KB 463201 356862 0.046 0.004 22.96 3167\n500KB-600KB 545123 429854 0.056 0.005 21.15 366\n600KB-700KB 647736 510931 0.065 0.006 21.12 254\n700KB-800KB 746540 587287 0.073 0.008 21.33 294\n800KB-900KB 868121 682650 0.087 0.008 21.36 199\n900KB-1MB 945747 726307 0.091 0.010 23.20 304\n\nOn 10/11/2015 8:46 AM, Jeff Garzik via bitcoin-dev wrote:\n\u003e Comments:\n\u003e\n\u003e 1) cblock seems a reasonable way to extend the protocol. Further\n\u003e wrapping should probably be done at the stream level.\n\u003e\n\u003e 2) zlib has crappy security track record.\n\u003e\n\u003e 3) A fallback path to non-compressed is required, should compression\n\u003e fail or crash.\n\u003e\n\u003e 4) Most blocks and transactions have runs of zeroes and/or highly\n\u003e common bit-patterns, which contributes to useful compression even at\n\u003e smaller sizes. Peter Ts's most recent numbers bear this out. zlib\n\u003e has a dictionary (32K?) which works well with repeated patterns such\n\u003e as those you see with concatenated runs of transactions.\n\u003e\n\u003e 5) LZO should provide much better compression, at a cost of CPU\n\u003e performance and using a less-reviewed, less-field-tested library.\n\u003e\n\u003e\n\u003e\n\u003e\n\u003e\n\u003e On Tue, Nov 10, 2015 at 11:30 AM, Tier Nolan 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\n\u003e\n\u003e On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper\n\u003e \u003cpeter.tschipper at gmail.com \u003cmailto:peter.tschipper at gmail.com\u003e\u003e wrote:\n\u003e\n\u003e There are better ways of sending new blocks, that's certainly\n\u003e true but for sending historical blocks and seding transactions\n\u003e I don't think so. This PR is really designed to save\n\u003e bandwidth and not intended to be a huge performance\n\u003e improvement in terms of time spent sending.\n\u003e\n\u003e\n\u003e If the main point is for historical data, then sticking to just\n\u003e blocks is the best plan.\n\u003e\n\u003e Since small blocks don't compress well, you could define a\n\u003e \"cblocks\" message that handles multiple blocks (just concatenate\n\u003e the block messages as payload before compression). \n\u003e\n\u003e The sending peer could combine blocks so that each cblock is\n\u003e compressing at least 10kB of block data (or whatever is optimal). \n\u003e It is probably worth specifying a maximum size for network buffer\n\u003e reasons (either 1MB or 1 block maximum).\n\u003e\n\u003e Similarly, transactions could be combined together and compressed\n\u003e \"ctxs\". The inv messages could be modified so that you can\n\u003e request groups of 10-20 transactions. That would depend on how\n\u003e much of an improvement compressed transactions would represent.\n\u003e\n\u003e More generally, you could define a message which is a compressed\n\u003e message holder. That is probably to complex to be worth the\n\u003e effort though.\n\u003e\n\u003e \n\u003e\n\u003e\u003e\n\u003e\u003e On Tue, Nov 10, 2015 at 5:40 AM, Johnathan Corgan via\n\u003e\u003e bitcoin-dev \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 On Mon, Nov 9, 2015 at 5:58 PM, gladoscc 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 I think 25% bandwidth savings is certainly\n\u003e\u003e considerable, especially for people running full\n\u003e\u003e nodes in countries like Australia where internet\n\u003e\u003e bandwidth is lower and there are data caps.\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e ā This reinforces the idea that such trade-off decisions\n\u003e\u003e should be be local and negotiated between peers, not a\n\u003e\u003e required feature of the network P2P.ā\n\u003e\u003e \n\u003e\u003e\n\u003e\u003e -- \n\u003e\u003e Johnathan Corgan\n\u003e\u003e Corgan Labs - SDR Training and Development Services\n\u003e\u003e http://corganlabs.com\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 _______________________________________________\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 bitcoin-dev mailing list\n\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151111/b008e0c1/attachment.html\u003e",
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