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From: Luke Dashjr <luke@dashjr.org>
To: bitcoin-dev@lists.linuxfoundation.org,
	Sergio Demian Lerner <sergio.d.lerner@gmail.com>
Subject: Re: [bitcoin-dev] A Segwit2x BIP
Date: Fri, 7 Jul 2017 23:27:14 +0000	[thread overview]
Message-ID: <201707072327.15901.luke@dashjr.org> (raw)
In-Reply-To: <CAKzdR-qCmuj02yobAj9YDYq7Ed309z2VUaMtbL_i9vF3zkp5mw@mail.gmail.com>

> Maximum transaction size is kept, to maximize compatibility with current
> software and prevent algorithmic and data size DoS's.

IIRC, it is actually increased by ~81 bytes, and doesn't count witness data if 
on Segwit transactions (so in effect, nearly 4 MB transactions are possible). 
This probably doesn't make the hashing problem worse, however it should be 
made clear in the BIP.

> Assuming the current transaction pattern is replicated in a 2 MB
> plain-sized block that is 100% filled with transactions, then the
> witness-serialized block would occupy 3.6 MB [1]. This is considered safe
> by many users, companies, miners and academics [2].

Citations do not support the claim.

> The plain block size is defined as the serialized block size without
> witness programs.

This is deceptive and meaningless. There is no reason to *ever* refer to the 
size of the block serialised without witness programs. It is not a meaningful 
number.

> Deploy a modified BIP91 to activate Segwit. The only modification is that
> the signal "segsignal" is replaced by "segwit2x".

What is modified here? "segsignal" does not appear in the BIP 91 protocol at 
all...

> If segwit2x (BIP91 signal) activates at block N, then block N+12960
> activates a new plain block size limit of 2 MB (2,000,000 bytes). In this
> case, at block N+12960 a hard-fork occurs.

A "plain block size limit" of 2 MB would be a no-op. It would have literally 
no effect whatsoever on the network rules.

Furthermore, this does not match what btc1/Segwit2x currently implements at 
all. The actual implementation is: If Segwit (via deployment method) activates 
at block N, then block N+12960 activates a new weight limit of 8M (which 
corresponds to a size of up to 8,000,000 bytes).

> Any transaction with a non-witness serialized size exceeding 1,000,000 is
> invalid.

What is the rationale for excluding witness data from this measurement?

> In the short term, an increase is needed to continue to facilitate network
> growth, and buy time...

Actual network growth does not reflect a pattern that supports this claim.

> This reduces the fee pressure on users and companies creating on-chain
> transactions, matching market expectations and preventing further market
> disruption.

Larger block sizes is not likely to have a meaningful impact on fee pressure. 
Any expectations that do not match the reality are merely misguided, and 
should not be a basis for changing Bitcoin.

Luke


  parent reply	other threads:[~2017-07-07 23:28 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-07 22:25 [bitcoin-dev] A Segwit2x BIP Sergio Demian Lerner
2017-07-07 22:44 ` Matt Corallo
2017-07-07 23:25   ` Gregory Maxwell
2017-07-07 23:22 ` Gregory Maxwell
2017-07-13  3:10   ` Sergio Demian Lerner
2017-07-13  3:19     ` Sergio Demian Lerner
2017-07-07 23:27 ` Luke Dashjr [this message]
2017-07-07 23:38   ` Gregory Maxwell
2017-07-08  6:30 ` Erik Aronesty
2017-07-08 13:28 ` Btc Drak
     [not found]   ` <A7FFF8F7-9806-44F1-B68F-F83C44893365@ob1.io>
2017-07-10 11:50     ` Sergio Demian Lerner
2017-07-10 18:38       ` Jorge Timón
2017-07-12  8:15         ` Tom Zander
2017-07-12 12:38           ` Jonas Schnelli
2017-07-12 17:38           ` Jorge Timón
2017-07-13 19:19             ` Sergio Demian Lerner
2017-07-13 19:48               ` Andrew Chow
2017-07-13 21:18                 ` Charlie 'Charles' Shrem
2017-07-14 13:50               ` Erik Aronesty
2017-07-12  1:06       ` Luke Dashjr
2017-07-12 15:41         ` Aymeric Vitte

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