public inbox for bitcoindev@googlegroups.com
 help / color / mirror / Atom feed
From: "Hampus Sjöberg" <hampus.sjoberg@gmail.com>
To: s7r@sky-ip.org,
	 Bitcoin Protocol Discussion
	<bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty (aka Block75)
Date: Sat, 10 Dec 2016 13:05:22 +0100	[thread overview]
Message-ID: <CAFMkqK9v6OkNd04FvfMfk+1zYtvZwm0dgx8L=J0ehn0iuyVVoA@mail.gmail.com> (raw)
In-Reply-To: <c318f76d-0904-2e1b-453b-60179f8209bb@sky-ip.org>

[-- Attachment #1: Type: text/plain, Size: 5340 bytes --]

> While disk space requirements might not be a big problem, block
propagation time is

Is block propagation time really still a problem? Compact blocks and FIBRE
should help here.

> Bitcoin, because its fundamental design, can scale by using offchain
solutions.

I agree.
However, I believe that on-chain scaling will be needed regardless of which
off-chain solution gains popularity.

2016-12-10 11:44 GMT+01:00 s7r via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org>:

> t. khan via bitcoin-dev wrote:
> > BIP Proposal - Managing Bitcoin’s block size the same way we do
> > difficulty (aka Block75)
> >
> > The every two-week adjustment of difficulty has proven to be a
> > reasonably effective and predictable way of managing how quickly blocks
> > are mined. Bitcoin needs a reasonably effective and predictable way of
> > managing the maximum block size.
> >
> > It’s clear at this point that human beings should not be involved in the
> > determination of max block size, just as they’re not involved in
> > deciding the difficulty.
> >
> > Instead of setting an arbitrary max block size (1MB, 2MB, 8MB, etc.) or
> > passing the decision to miners/pool operators, the max block size should
> > be adjusted every two weeks (2016 blocks) using a system similar to how
> > difficulty is calculated.
> >
> > Put another way: let’s stop thinking about what the max block size
> > should be and start thinking about how full we want the average block to
> > be regardless of size. Over the last year, we’ve had averages of 75% or
> > higher, so aiming for 75% full seems reasonable, hence naming this
> > concept ‘Block75’.
> >
> > The target capacity over 2016 blocks would be 75%. If the last 2016
> > blocks are more than 75% full, add the difference to the max block size.
> > Like this:
> >
> > MAX_BLOCK_BASE_SIZE = 1000000
> > TARGET_CAPACITY = 750000
> > AVERAGE_OVER_CAP = average block size of last 2016 blocks minus
> > TARGET_CAPACITY
> >
> > To check if a block is valid, ≤ (MAX_BLOCK_BASE_SIZE + AVERAGE_OVER_CAP)
> >
> > For example, if the last 2016 blocks are 85% full (average block is 850
> > KB), add 10% to the max block size. The new max block size would be
> > 1,100 KB until the next 2016 blocks are mined, then reset and
> > recalculate. The 1,000,000 byte limit that exists currently would
> > remain, but would effectively be the minimum max block size.
> >
> > Another two weeks goes by, the last 2016 blocks are again 85% full, but
> > now that means they average 935 KB out of the 1,100 KB max block size.
> > This is 93.5% of the 1,000,000 byte limit, so 18.5% would be added to
> > that to make the new max block size of 1,185 KB.
> >
> > Another two weeks passes. This time, the average block is 1,050 KB. The
> > new max block size is calculated to 1,300 KB (as blocks were 105% full,
> > minus the 75% capacity target, so 30% added to max block size).
> >
> > Repeat every 2016 blocks, forever.
> >
> > If Block75 had been applied at the difficulty adjustment on November
> > 18th, the max block size would have been 1,080KB, as the average block
> > during that period was 83% full, so 8% is added to the 1,000KB limit.
> > The current size, after the December 2nd adjustment would be 1,150K.
> >
> > Block75 would allow the max block size to grow (or shrink) in response
> > to transaction volume, and does so predictably, reasonably quickly, and
> > in a method that prevents wild swings in block size or transaction fees.
> > It attempts to keep blocks at 75% total capacity over each two week
> > period, the same way difficulty tries to keep blocks mined every ten
> > minutes. It also keeps blocks as small as possible.
> >
> > Thoughts?
> >
> > -t.k.
> >
>
> I like the idea. It is good wrt growing the max. block size
> automatically without human action, but the main problem (or question)
> is not how to grow this number, it is what number can the network
> handle, considering both miners and users. While disk space requirements
> might not be a big problem, block propagation time is. The time required
> for a block to propagate in the network (or at least to all the miners)
> is directly dependent of its size.  If blocks take too much time to
> propagate in the network, the orphan rate will increase in unpredictable
> ways. For example if the internet speed in China is worse than in
> Europe, and miners in China have more than 50% of the hashing power,
> blocks mined by European miners might get orphaned.
>
> The system as described can also be gamed, by filling the network with
> transactions. Miners have the monetary interest to include as many
> transactions as possible in a block in order to collect the fees.
> Regardless how you think about it, there has to be a maximum block size
> that the network will allow as a consensus rule. Increasing it
> dynamically based on transaction volume will reach a point where the
> number got big enough that it broke things. Bitcoin, because its
> fundamental design, can scale by using offchain solutions.
>
>
> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>
>

[-- Attachment #2: Type: text/html, Size: 6328 bytes --]

  reply	other threads:[~2016-12-10 12:05 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-12-05 15:27 [bitcoin-dev] Managing block size the same way we do difficulty (aka Block75) t. khan
2016-12-10 10:44 ` s7r
2016-12-10 12:05   ` Hampus Sjöberg [this message]
2016-12-11  0:26   ` t. khan
2016-12-11  0:40     ` James Hilliard
2016-12-11  1:07       ` Bram Cohen
2016-12-11 17:11     ` s7r
2016-12-11 19:55       ` t. khan
2016-12-11 20:31         ` James Hilliard
2016-12-11 21:40           ` t. khan
2016-12-11 21:53             ` Bram Cohen
2016-12-11 21:55             ` James Hilliard
2016-12-11 22:30               ` t. khan
2016-12-11 20:38       ` Andrew Johnson
2016-12-11 23:22         ` s7r
2016-12-18 21:53           ` James MacWhyte
2016-12-19  1:42             ` Tom Harding
2016-12-10 23:12 ` Bram Cohen
2016-12-11  0:52   ` t. khan
     [not found] <CAEgR2PEMPo3veqJat7OAps1DzTSNFJmJiRbkFgYKvYfxqdbUiw@mail.gmail.com>
     [not found] ` <CAEgR2PELB1_s+o0Bj4Kj9vS27eoqP7gV_VS_6QHQtTUAOnMORg@mail.gmail.com>
     [not found]   ` <CAEgR2PFpGWxngq=fKGi7CC_d+=5YWzWwbEEsQNEifCuHAAPAHw@mail.gmail.com>
     [not found]     ` <CAEgR2PHnrsdaBiDgywvE9amK8_yPE_hBo0yYOYwUk4T8n7wnAQ@mail.gmail.com>
     [not found]       ` <CAEgR2PEgPkRe76hW0Jj7_Z1EdmmNTpTAOKGm_of2dG=XXUOtnA@mail.gmail.com>
     [not found]         ` <CAEgR2PHew+fcJWnAt+t8umcwKu4TkshH=AFJ-8MeYysud2MkBQ@mail.gmail.com>
     [not found]           ` <CAEgR2PEVwt_shiqwGjK6dPscRUTHayis0PaQO5Dj_fVEGGgaCQ@mail.gmail.com>
2016-12-10 12:23             ` Daniele Pinna
2016-12-10 17:39               ` Pieter Wuille
2016-12-11  3:17                 ` Daniele Pinna
2016-12-11  5:29                   ` Eric Voskuil
2016-12-11  9:21                   ` Adam Back

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAFMkqK9v6OkNd04FvfMfk+1zYtvZwm0dgx8L=J0ehn0iuyVVoA@mail.gmail.com' \
    --to=hampus.sjoberg@gmail.com \
    --cc=bitcoin-dev@lists.linuxfoundation.org \
    --cc=s7r@sky-ip.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox