📅 Original date posted:2015-11-11
📝 Original message: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> 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>
> bitcoin-dev at lists.linuxfoundation.org> wrote:
>
>>
>>
>> On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper <
>> <peter.tschipper at gmail.com>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>
>>> 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>
>>>> 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>http://corganlabs.com
>>>>
>>>> _______________________________________________
>>>> bitcoin-dev mailing list
>>>> bitcoin-dev at lists.linuxfoundation.org
>>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>>>>
>>>>
>>>
>>>
>>> _______________________________________________
>>> bitcoin-dev mailing listbitcoin-dev at lists.linuxfoundation.orghttps://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
>>
>>
>
>
> _______________________________________________
> bitcoin-dev mailing listbitcoin-dev at lists.linuxfoundation.orghttps://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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Marco Pontello [ARCHIVE] /
npub12s…wdn3h
2023-06-07 17:44:25
in reply to nevent1q…skrx
Author Public Key
npub12srjs7mc5grqhm86mngax037h3v75wvx8tpd55cfhmkj6dagqxrqmwdn3hPublished at
2023-06-07 17:44:25Event JSON
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"content": "📅 Original date posted:2015-11-11\n📝 Original message:A random thought: aren't most communication over a data link already\ncompressed, at some point?\nWhen I used a modem, we had the V.42bis protocol. Now, nearly all ADSL\nconnections using PPPoE, surely are. And so on.\nI'm not sure another level of generic, data agnostic kind of compression\nwill really give us some real-life practical advantage over that.\n\nSomething that could take advantage of of special knowledge of the specific\ndata, instead, would be an entirely different matter.\n\nJust my 2c.\n\nOn Wed, Nov 11, 2015 at 7:35 PM, Peter Tschipper via bitcoin-dev \u003c\nbitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\n\u003e Here are the latest results on compression ratios for the first 295,000\n\u003e blocks, compressionlevel=6. I think there are more than enough datapoints\n\u003e for statistical significance.\n\u003e\n\u003e Results are very much similar to the previous test. I'll work on getting\n\u003e a comparison between how much time savings/loss in time there is when\n\u003e syncing the blockchains: compressed vs uncompressed. Still, I think it's\n\u003e clear that serving up compressed blocks, at least historical blocks, will\n\u003e be of benefit for those that have bandwidth caps on their internet\n\u003e connections.\n\u003e\n\u003e The proposal, so far is fairly simple:\n\u003e 1) compress blocks with some compression library: currently zlib but I can\n\u003e investigate other possiblities\n\u003e 2) As a fall back we need to advertise compression as a service. That way\n\u003e we can turn off compression AND decompression completely if needed.\n\u003e 3) Do the compression at the datastream level in the code. CDataStream is\n\u003e 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% datapoints\n\u003e 0-250b 215 189 0.001 0.000 12.40 91280\n\u003e 250-500b 438 404 0.001 0.000 7.85 13217\n\u003e 500-1KB 761 701 0.001 0.000 7.86\n\u003e 11434\n\u003e 1KB-10KB 4149 3547 0.001 0.000 14.51 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\n\u003e Comments:\n\u003e\n\u003e 1) cblock seems a reasonable way to extend the protocol. Further wrapping\n\u003e 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 fail\n\u003e or crash.\n\u003e\n\u003e 4) Most blocks and transactions have runs of zeroes and/or highly common\n\u003e bit-patterns, which contributes to useful compression even at smaller\n\u003e sizes. Peter Ts's most recent numbers bear this out. zlib has a\n\u003e dictionary (32K?) which works well with repeated patterns such as those you\n\u003e 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 \u003c\n\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\n\u003e\u003e\n\u003e\u003e\n\u003e\u003e On Tue, Nov 10, 2015 at 4:11 PM, Peter Tschipper \u003c\n\u003e\u003e \u003cpeter.tschipper at gmail.com\u003epeter.tschipper at gmail.com\u003e wrote:\n\u003e\u003e\n\u003e\u003e\u003e There are better ways of sending new blocks, that's certainly true but\n\u003e\u003e\u003e for sending historical blocks and seding transactions I don't think so.\n\u003e\u003e\u003e This PR is really designed to save bandwidth and not intended to be a huge\n\u003e\u003e\u003e performance improvement in terms of time spent sending.\n\u003e\u003e\u003e\n\u003e\u003e\n\u003e\u003e If the main point is for historical data, then sticking to just blocks is\n\u003e\u003e the best plan.\n\u003e\u003e\n\u003e\u003e Since small blocks don't compress well, you could define a \"cblocks\"\n\u003e\u003e message that handles multiple blocks (just concatenate the block messages\n\u003e\u003e as payload before compression).\n\u003e\u003e\n\u003e\u003e The sending peer could combine blocks so that each cblock is compressing\n\u003e\u003e at least 10kB of block data (or whatever is optimal). It is probably worth\n\u003e\u003e specifying a maximum size for network buffer reasons (either 1MB or 1 block\n\u003e\u003e maximum).\n\u003e\u003e\n\u003e\u003e Similarly, transactions could be combined together and compressed\n\u003e\u003e \"ctxs\". The inv messages could be modified so that you can request groups\n\u003e\u003e of 10-20 transactions. That would depend on how much of an improvement\n\u003e\u003e compressed transactions would represent.\n\u003e\u003e\n\u003e\u003e More generally, you could define a message which is a compressed message\n\u003e\u003e holder. That is probably to complex to be 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 bitcoin-dev \u003c\n\u003e\u003e\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e On Mon, Nov 9, 2015 at 5:58 PM, gladoscc via bitcoin-dev \u003c\n\u003e\u003e\u003e\u003e \u003cbitcoin-dev at lists.linuxfoundation.org\u003e\n\u003e\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\u003e wrote:\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e\u003e I think 25% bandwidth savings is certainly considerable, especially\n\u003e\u003e\u003e\u003e\u003e for people running full nodes in countries like Australia where internet\n\u003e\u003e\u003e\u003e\u003e bandwidth is lower and there are data caps.\n\u003e\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e This reinforces the idea that such trade-off decisions should be be\n\u003e\u003e\u003e\u003e local and negotiated between peers, not a required feature of the network\n\u003e\u003e\u003e\u003e P2P.\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e --\n\u003e\u003e\u003e\u003e Johnathan Corgan\n\u003e\u003e\u003e\u003e Corgan Labs - SDR Training and Development Services\n\u003e\u003e\u003e\u003e \u003chttp://corganlabs.com\u003ehttp://corganlabs.com\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e _______________________________________________\n\u003e\u003e\u003e\u003e bitcoin-dev mailing list\n\u003e\u003e\u003e\u003e bitcoin-dev at lists.linuxfoundation.org\n\u003e\u003e\u003e\u003e https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\u003e\u003e _______________________________________________\n\u003e\u003e\u003e bitcoin-dev mailing listbitcoin-dev at lists.linuxfoundation.orghttps://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\u003e\n\u003e\u003e\u003e\n\u003e\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 https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\u003e\n\u003e\u003e\n\u003e\n\u003e\n\u003e _______________________________________________\n\u003e bitcoin-dev mailing listbitcoin-dev at lists.linuxfoundation.orghttps://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 https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev\n\u003e\n\u003e\n\n\n-- \nTry the Online TrID File Identifier\nhttp://mark0.net/onlinetrid.aspx\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20151111/0430cab2/attachment-0001.html\u003e",
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