From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 62F85CF8 for ; Sat, 29 Aug 2015 09:39:47 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from s47.web-hosting.com (s47.web-hosting.com [199.188.200.16]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 2BCA41AE for ; Sat, 29 Aug 2015 09:39:38 +0000 (UTC) Received: from localhost ([::1]:48702 helo=server47.web-hosting.com) by server47.web-hosting.com with esmtpa (Exim 4.85) (envelope-from ) id 1ZVcac-0029P7-HF; Sat, 29 Aug 2015 05:38:22 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Date: Sat, 29 Aug 2015 05:38:17 -0400 From: jl2012@xbt.hk To: Btc Drak In-Reply-To: References: Message-ID: X-Sender: jl2012@xbt.hk User-Agent: Roundcube Webmail/1.0.5 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - server47.web-hosting.com X-AntiAbuse: Original Domain - lists.linuxfoundation.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - xbt.hk X-Get-Message-Sender-Via: server47.web-hosting.com: authenticated_id: jl2012@xbt.hk X-Source: X-Source-Args: X-Source-Dir: X-From-Rewrite: unmodified, already matched X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] Consensus based block size retargeting algorithm (draft) X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 29 Aug 2015 09:39:47 -0000 We need some game theory experts to analyse this but I see there are 3 major problems: 1. Tragedy of the commons: Some miners have to scarify their income to increase the block size, and all miners will share the beneficial outcome of the increase. All miners would like to be free riders. 2. Promote the formation of mining cartel: miners have to make sure that their vote for increase is supported by at least 50% of miners, or they will lose income for nothing. A miner also needs to make sure that he is not voting "excessively" (in terms of size and vote count), as the excessive part will never be counted due to the use of median. So basically you will either have exactly 1009 miners voting for the same size increase in a cycle, or have no vote for increase at all. That will require a lot of offline negotiations. Such cartel may work ONLY if mining is highly centralized, and miners trust each other. Also, there is no mechanism to punish those who betray the cartel. 3. Imbalance of power: it is costly to increase the size, while totally free to decrease the size Btc Drak via bitcoin-dev 於 2015-08-28 16:28 寫到: > I have received a lot of feedback on the original gist[1], reddit[2], > ML and IRC and have reworked the text somewhat. > > I also request the BIP maintainer for a BIP number assignment > > [1] https://gist.github.com/btcdrak/1c3a323100a912b605b5 > [2] > https://www.reddit.com/r/Bitcoin/comments/3ibia0/bipxx_consensus_based_block_size_retargeting/ > > Pull request: https://github.com/bitcoin/bips/pull/187 > > 
>   BIP: XX
>   Title: Consensus based block size retargeting algorithm
>   Author: BtcDrak 
>   Status: Draft
>   Type: Standards Track
>   Created: 2015-08-21
>
> > ==Abstract== > > A method of altering the maximum allowed block size of the Bitcoin > protocol > using a consensus based approach. > > ==Motivation== > > There is a belief that Bitcoin cannot easily respond to raising the > blocksize limit if popularity was to suddenly increase due to a mass > adoption > curve, because co-ordinating a hard fork takes considerable time, and > being > unable to respond in a timely manner would irreparably harm the > credibility of > bitcoin. > > Additionally, predetermined block size increases are problematic > because they > attempt to predict the future, and if too large could have unintended > consequences like damaging the possibility for a fee market to develop > as block subsidy decreases substantially over the next 9 years; > introducing > or exacerbating mining attack vectors; or somehow affect the network in > unknown > or unpredicted ways. Since fixed changes are hard to deploy, the damage > could be > extensive. > > Dynamic block size adjustments also suffer from the potential to be > gamed by the > larger hash power. > > Free voting as suggested by BIP100 allows miners to sell their votes > out of band > at no risk, and enable the sponsor the ability to manipulate the > blocksize. > It also provides a cost free method or the larger pools to vote in ways > to > manipulate the blocksize such to disadvantage or attack smaller pools. > > > ==Rationale== > > By introducing a cost to increase the block size ensures the mining > community > will collude to increase it only when there is a clear necessity, and > reduce it > when it is unnecessary. Larger miners cannot force their wishes so > easily > because not only will they have to pay extra a difficulty target, then > can be > downvoted at no cost by the objecting hash power. > > Using difficulty as a penalty is better than a fixed cost in bitcoins > because it > is less predictable. > > > ==Specification== > > The initial block size limit shall be 1MB. > > Each time a miner creates a block, they may vote to increase or > decrease the > blocksize by a maximum of 10% of the current block size limit. These > votes will > be used to recalculate the new block size limit every 2016 blocks. > > Votes are cast using the block's coinbase field. > > The first 4 bytes of the coinbase field shall be repurposed for voting > as an > unsigned long integer which will be the block size in bytes. > > If a miner votes for an increase, the block hash must meet a difficulty > target > which is proportionally larger than the standard difficulty target > based on the > percentage increase they voted for. > > Votes proposing decreasing the block size limit do not need to meet a > higher > difficulty target. > > Miners can vote for no change by voting for the current block size. > > For blocks to be valid the blockhash must meet the required difficulty > target > for the vote otherwise the block is invalid and will be rejected. > > Every 2016 blocks, the block size limit will be recalculated by the > median of > all votes in the last 2016 blocks. This will redefine the block size > limit for > the next 2016 blocks. > > Blocks that are larger than the calculated base block size limit are > invalid and > will be rejected. > > The base block size limit may not reduce below 1MB. > > > ==Acknowledgements== > > This proposal is based on ideas and concepts derived from the writings > of > Meni Rosenfeld and Gregory Maxwell. > > > ==Copyright== > > This work is placed in the public domain. > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev