Personally, I would prefer if a 2MB lock-in that uses BIP103 for the
timing.

I think up to 20% per year can be absorbed by averages in bandwidth/CPU/RAM
growth, of which bandwidth seems the most constraining.

- Erik


On Tue, May 23, 2017 at 4:23 PM, Luke Dashjr via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> In light of some recent discussions, I wrote up this BIP for a real 2 MB
> block
> size hardfork following Segwit BIP148 activation. This is not part of any
> agreement I am party to, nor anything of that sort. Just something to throw
> out there as a possible (and realistic) option.
>
> Note that I cannot recommend this to be adopted, since frankly 1 MB blocks
> really are still too large, and this blunt-style hardfork quite risky even
> with consensus. But if the community wishes to adopt (by unanimous
> consensus)
> a 2 MB block size hardfork, this is probably the best way to do it right
> now.
> The only possible way to improve on this IMO would be to integrate it into
> MMHF/"spoonnet" style hardfork (and/or add other unrelated-to-block-size HF
> improvements).
>
> I have left Author blank, as I do not intend to personally champion this.
> Before it may be assigned a BIP number, someone else will need to step up
> to
> take on that role. Motivation and Rationale are blank because I do not
> personally think there is any legitimate rationale for such a hardfork at
> this
> time; if someone adopts this BIP, they should complete these sections. (I
> can
> push a git branch with the BIP text if someone wants to fork it.)
>
> <pre>
> BIP: ?
> Layer: Consensus (hard fork)
> Title: Post-segwit 2 MB block size hardfork
> Author: FIXME
> Comments-Summary: No comments yet.
> Comments-URI: ?
> Status: Draft
> Type: Standards Track
> Created: 2017-05-22
> License: BSD-2-Clause
> </pre>
>
> ==Abstract==
>
> Legacy Bitcoin transactions are given the witness discount, and a block
> size
> limit of 2 MB is imposed.
>
> ==Copyright==
>
> This BIP is licensed under the BSD 2-clause license.
>
> ==Specification==
>
> Upon activation, a block size limit of 2000000 bytes is enforced.
> The block weight limit remains at 4000000 WU.
>
> The calculation of block weight is modified:
> all witness data, including both scriptSig (used by pre-segwit inputs) and
> segwit witness data, is measured as 1 weight-unit (WU), while all other
> data
> in the block is measured as 4 WU.
>
> The witness commitment in the generation transaction is no longer required,
> and instead the txid merkle root in the block header is replaced with a
> hash
> of:
>
> 1. The witness reserved value.
> 2. The witness merkle root hash.
> 3. The transaction ID merkle root hash.
>
> The maximum size of a transaction stripped of witness data is limited to 1
> MB.
>
> ===Deployment===
>
> This BIP is deployed by flag day, in the block where the median-past time
> surpasses 1543503872 (2018 Nov 29 at 15:04:32 UTC).
>
> It is assumed that when this flag day has been reached, Segwit has been
> activated via BIP141 and/or BIP148.
>
> ==Motivation==
>
> FIXME
>
> ==Rationale==
>
> FIXME
>
> ==Backwards compatibility==
>
> This is a hardfork, and as such not backward compatible.
> It should not be deployed without consent of the entire Bitcoin community.
> Activation is scheduled for 18 months from the creation date of this BIP,
> intended to give 6 months to establish consensus, and 12 months for
> deployment.
>
> ==Reference implementation==
>
> FIXME
>
>
>
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>