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 7DCABDB1 for ; Thu, 3 Sep 2015 11:20:30 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 91B4910D for ; Thu, 3 Sep 2015 11:20:29 +0000 (UTC) Received: by wicfx3 with SMTP id fx3so16255537wic.1 for ; Thu, 03 Sep 2015 04:20:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:content-transfer-encoding; bh=EH9BpYKSSP5ERw8BQGu2/ii/kwS8Jy7/VmyBipijASM=; b=P6yM84QzgnF3zhLjYNLGJyStEUMDwLop0IM42NJgDnWWbFpPMXmDaMMQPBPpJi/Ok6 nDH5FN7P6JJKJBzXCvXccix261K7b5bXx1t0vNNR+Bv9SuSCGJYIxZtcUCB6yMs+jNnV 8mYq3SHjmnU+Gf4f+90lmhE9uJJdcPB5tD4M8bLkQd9oZ4QGwiNsrUnjAICUx1B+Y194 OxNchYzw+wissahvdIokGV4KQymsw8so8HzcvylGrnxn6FRYKSe/A5HYC0a/72G+wwCI VITNJIGoQ4YdsnmQ+h97CuDIw63nww9QC5ONCwoEp/xcwo1JPAp/1jaUTKPBXLts2CJb 2Xvg== X-Received: by 10.180.187.170 with SMTP id ft10mr13241175wic.15.1441279228069; Thu, 03 Sep 2015 04:20:28 -0700 (PDT) MIME-Version: 1.0 Received: by 10.28.26.10 with HTTP; Thu, 3 Sep 2015 04:20:08 -0700 (PDT) In-Reply-To: References: From: Btc Drak Date: Thu, 3 Sep 2015 12:20:08 +0100 Message-ID: To: jl2012@xbt.hk Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-1.7 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HK_RANDOM_ENVFROM, HK_RANDOM_FROM, RCVD_IN_DNSWL_LOW autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin development mailing list Subject: Re: [bitcoin-dev] BIP 100 specification 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: Thu, 03 Sep 2015 11:20:30 -0000 We should avoid discussing actual hard fork/softfork deployment methodologies when discussing blocksize proposals because deployment is a separate issue. As a recent case in point, look at how BIP65 (CHECKLOCKTIMEVERIFY) specifically avoided the issue of how to deploy. That lead to a focused discussion of the functionality and relatively quick inclusion. Deployment really is a separate issue than the mechanics of how BIP100 will function after activation. On Thu, Sep 3, 2015 at 8:57 AM, jl2012 via bitcoin-dev wrote: > Some comments: > > The 75% rule is meaningless here. Since this is a pure relaxation of rule= s, > there is no such thing as "invalid version 4 blocks" > > The implication threshold is unclear. Is it 95% or 80%? > > Softfork requires a very high threshold (95%) to "attack" the original fo= rk. > This makes sure that unupgraded client will only see the new fork. > In the case of hardfork, however, the new fork is unable to attack the > original fork, and unupgraded client will never see the new fork. The > initiation of a hardfork should be based on its acceptance by the economi= c > majority, not miner support. 95% is an overkill and may probably never > accomplished. I strongly prefer a 80% threshold rather than 95%. > > As I've pointed out, using 20-percentile rather than median creates an > incentive to 51% attack the uncooperative minority. > https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2015-August/01069= 0.html > > Having said that, I don't have a strong feeling about the use of > 20-percentile as threshold to increase the block size. That means the blo= ck > size is increased only when most miners agree, which sounds ok to me. > > However, using 20-percentile as threshold to DECREASE the block size coul= d > be very dangerous. Consider that the block size has been stable at 8MB fo= r a > few years. Everyone are happy with that. An attacker would just need to > acquire 21% of mining power to break the status quo and send us all the w= ay > to 1MB. The only way to stop such attempt is to 51% attack the attacker. > That'd be really ugly. > > For technical and ethical reasons, I believe the thresholds for increase = and > decrease must be symmetrical: increase the block size when the x-percenti= le > is bigger than the current size, decrease the block size when the > (100-x)-percentile is smaller than the current size. The overall effect i= s: > the block size remains unchanged unless 80% of miners agree to. > > Please consider the use of "hardfork bit" to signify the hardfork: > > https://www.reddit.com/r/bitcoin_devlist/comments/3ekhg2/bip_draft_hardfo= rk_bit_jl2012_at_xbthk_jul_23_2015/ > > https://github.com/jl2012/bips/blob/master/hardforkbit.mediawiki > > Or, alternatively, please combine the hardfork with a softfork. I'm > rewriting the specification as follow (changes underlined): > > Replace static 1M block size hard limit with a floating limit ("hardLimit= "). > > hardLimit floats within the range 1-32M, inclusive. > > Initial value of hardLimit is 1M, preserving current system. > > Changing hardLimit is accomplished by encoding a proposed value within a > block's coinbase scriptSig. > > Votes refer to a byte value, encoded within the pattern "/BV\d+/" Example= : > /BV8000000/ votes for 8,000,000 byte hardLimit. If there is more than one > match with with pattern, the first match is counted. > Absent/invalid votes and votes below minimum cap (1M) are counted as 1M > votes. Votes above the maximum cap (32M) are counted as 32M votes. > A new hardLimit is calculated at each difficult adjustment period (2016 > blocks), and applies to the next 2016 blocks. > Calculate hardLimit by examining the coinbase scriptSig votes of the > previous 12,000 blocks, and taking the 20th percentile and 80th percentil= e. > New hardLimit is the median of the followings: > > min(current hardLimit * 1.2, 20-percentile) > max(current hardLimit / 1.2, 80-percentile) > current hardLimit > > version 4 block: the coinbase of a version 4 block must match this patter= n: > "/BV\d+/" > 70% rule: If 8,400 of the last 12,000 blocks are version 4 or greater, > reject invalid version 4 blocks. (testnet4: 501 of last 1000) > 80% rule ("Point of no return"): If 9,600 of the last 12,000 blocks are > version 4 or greater, reject all version <=3D 3 blocks. (testnet4: 750 of= last > 1000) > Block version number is calculated after masking out high 16 bits (final = bit > count TBD by versionBits outcome). > > Jeff Garzik via bitcoin-dev =E6=96=BC 2015-09-02 23:33 =E5=AF=AB=E5=88=B0= : >> BIP 100 initial public draft: >> https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki [1] >> >> Emphasis on "initial" This is a starting point for the usual open >> source feedback/iteration cycle, not an endpoint that Must Be This >> Way. >> >> >> >> Links: >> ------ >> [1] https://github.com/jgarzik/bip100/blob/master/bip-0100.mediawiki >> >> _______________________________________________ >> bitcoin-dev mailing list >> bitcoin-dev@lists.linuxfoundation.org >> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >