Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 5843DFF for ; Wed, 5 Aug 2015 07:29:52 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f174.google.com (mail-io0-f174.google.com [209.85.223.174]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 808027C for ; Wed, 5 Aug 2015 07:29:51 +0000 (UTC) Received: by iodd187 with SMTP id d187so40972122iod.2 for ; Wed, 05 Aug 2015 00:29:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=aRexV9FAGex++jenREhg5Sqd/6oRkCKykp9O0mjPanI=; b=IIyKlhv17OgagItZ0f4T86WN1wXTXDljLbWQZXxqPKA2wJvd4JezjzTQcdlAKQdHuk Ja8XxY+THdAm1F4QeRxI/jZf6rjEaKXvndw/+NgNXa9rXkmdVeyIMdHqOzxgnGjZXQXm +xg7tPXAKFWwGXFlciPcqswk/SZOFYzjJMi5T2cakm2YYXfkIfqkY3q1BXTA77MrL9/l jHiZ26ztPaduV0a9P+DeuE/vJND7kkVHm2YKSYvAZeacnK4TNfqU+aKtXK1Zhc1AOGud EXfHh4BzWSsj0euIYMpqJYZd2qMqM74CdwOXNehFL+2P3/HzxaRgIkFRkb6Y/4hid+/l scqA== MIME-Version: 1.0 X-Received: by 10.107.17.170 with SMTP id 42mr8716417ior.21.1438759790968; Wed, 05 Aug 2015 00:29:50 -0700 (PDT) Received: by 10.79.97.4 with HTTP; Wed, 5 Aug 2015 00:29:50 -0700 (PDT) In-Reply-To: References: Date: Wed, 5 Aug 2015 00:29:50 -0700 Message-ID: From: Elliot Olds To: Bitcoin Dev Content-Type: multipart/alternative; boundary=001a113eca7e42064e051c8b5eb4 X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_05,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,HTML_MESSAGE,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 Subject: Re: [bitcoin-dev] Block size following technological growth 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: Wed, 05 Aug 2015 07:29:52 -0000 --001a113eca7e42064e051c8b5eb4 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On Tue, Aug 4, 2015 at 4:59 AM, Jorge Tim=C3=B3n < bitcoin-dev@lists.linuxfoundation.org> wrote: > > Also I don't think "hitting the limit" must be necessarily harmful and > if it is, I don't understand why hitting it at 1MB will be more > harmful than hitting it at 2MB, 8MB or 8GB. I don't think merely hitting the limit is bad. The level of tx fees in equilibrium give some clue as to the level of harm being done. If fees are at $5/tx at 1MB, it's about as bad as if fees are at $5/tx at 4MB. There is NO criterion based on mining centralization to decide between > 2 sizes in favor of the small one. > It seems like the rationale it's always "the bigger the better" and > the only limitation is what a few people concerned with mining > centralization (while they still have time to discuss this) are > willing to accept. If that's the case, then there won't be effectively > any limit in the long term and Bitcoin will probably fail in its > decentralization goals. > I think its the proponents of a blocksize change who should propose > such a criterion and now they have the tools to simulate different > block sizes. > In the absence of harder data, it might be interesting to use these simulations to graph centralization pressure as a function of bandwidth cost over time (or other historical variables that affect centralization). For instance, look at how high centralization pressure was in 2009 according to the simulations, given how cheap/available bandwidth was then, compared to 2010, 2011, etc. Then we could figure out: given today's bandwidth situation, what size blocks right now would give us the same centralization pressure that we had in 2011, 2012, 2013, etc? Of course this doesn't mean we should blindly assume that the level of centralization pressure in 2012 was acceptable, and therefore any block size increase that results in the same amount of pressure now should be acceptable. But it might lead to a more productive discussion. > I want us to simulate many blocksizes before rushing into a decision > (specially because I disagree that taking a decision there is urgent > in the first place). IMO it is not urgent if the core devs are committed to reacting to a huge spike in tx fees with a modest block size increase in a relatively short time frame, if they judge the centralization risks of that increase to be small. Greg Maxwell posted on reddit a while back something to the effect of "the big block advocates are overstating the urgency of the block size increase, because if there was actually a situation that required us to increase block size, we could make the increase when it was actually needed." I found that somewhat persuasive, but I am concerned that I haven't seen any discussion of what the "let's wait for now" camp would consider a valid reason to increase block size in the short term, and how they'd make the tradeoff with tx fees or whatever else was necessitating the increase. Jorge, if a fee equilibrium developed at 1MB of $5/tx, and you somehow knew with certainty that increasing to 4MB would result in a 20 cent/tx equilibrium that would last for a year (otherwise fees would stay around $5 for that year), would you be in favor of an increase to 4MB? For those familiar with the distinction between near/far mode thinking popularized by Robin Hanson: focusing on concrete examples like this encourages problem solving and consensus, and focusing on abstract principles (like decentralization vs. usability in general) leads to people toward using argument to signal their alliances and reduce the status of their opponents. I think it'd be very helpful if more 1MB advocates described what exactly would make them say "OK, in this situation a block size increase is needed, we should do one quickly!", and also if Gavin/Mike/Jeff described what hypothetical scenarios and/or test results would make them want to stick with 1MB blocks for now. --001a113eca7e42064e051c8b5eb4 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
On T= ue, Aug 4, 2015 at 4:59 AM, Jorge Tim=C3=B3n <bitcoin= -dev@lists.linuxfoundation.org> wrote:
Also I don't think "hitting the limit" must be necessarily ha= rmful and
if it is, I don't understand why hitting it at 1MB will be more
harmful than hitting it at 2MB, 8MB or 8GB.

I don't think merely hitting the limit is bad. The level of tx fees in= equilibrium give some clue as to the level of harm being done. If fees are= at $5/tx at 1MB, it's about as bad as if fees are at $5/tx at 4MB.=C2= =A0

There is NO criterion based on mining centralization to decide between
2 sizes in favor of the small one.
It seems like the rationale it's always "the bigger the better&quo= t; and
the only limitation is what a few people concerned with mining
centralization (while they still have time to discuss this) are
willing to accept. If that's the case, then there won't be effectiv= ely
any limit in the long term and Bitcoin will probably fail in its
decentralization goals.
I think its the proponents of a blocksize change who should propose
such a criterion and now they have the tools to simulate different
block sizes.

In the absence of harder d= ata, it might be interesting to use these simulations to graph centralizati= on pressure as a function of bandwidth cost over time (or other historical = variables that affect centralization). For instance, look at how high centr= alization pressure was in 2009 according to the simulations, given how chea= p/available bandwidth was then, compared to 2010, 2011, etc. Then we could = figure out: given today's bandwidth situation, what size blocks right n= ow would give us the same centralization pressure that we had in 2011, 2012= , 2013, etc?

Of course this doesn't mean we sh= ould blindly assume that the level of centralization pressure in 2012 was a= cceptable, and therefore any block size increase that results in the same a= mount of pressure now should be acceptable. But it might lead to a more pro= ductive discussion.
=C2=A0
I want us to simulate many blocksizes before rushing into a decision
(specially because I disagree that taking a decision there is urgent
in the first place).

IMO it is not urgent i= f the core devs are committed to reacting to a huge spike in tx fees with a= modest block size increase in a relatively short time frame, if they judge= the centralization risks of that increase to be small. Greg Maxwell posted= on reddit a while back something to the effect of "the big block advo= cates are overstating the urgency of the block size increase, because if th= ere was actually a situation that required us to increase block size, we co= uld make the increase when it was actually needed." I found that somew= hat persuasive, but I am concerned that I haven't seen any discussion o= f what the "let's wait for now" camp would consider a valid r= eason to increase block size in the short term, and how they'd make the= tradeoff with tx fees or whatever else was necessitating the increase.=C2= =A0

Jorge, if a fee equilibrium developed at 1MB o= f $5/tx, and you somehow knew with certainty that increasing to 4MB would r= esult in a 20 cent/tx equilibrium that would last for a year (otherwise fee= s would stay around $5 for that year), would you be in favor of an increase= to 4MB?=C2=A0

For those familiar with the distinc= tion between near/far mode thinking popularized by Robin Hanson: focusing o= n concrete examples like this encourages problem solving and consensus, and= focusing on abstract principles (like decentralization vs. usability in ge= neral) leads to people toward using argument to signal their alliances and = reduce the status of their opponents. I think it'd be very helpful if m= ore 1MB advocates described what exactly would make them say "OK, in t= his situation a block size increase is needed, we should do one quickly!&qu= ot;, and also if Gavin/Mike/Jeff described what hypothetical scenarios and/= or test results would make them want to stick with 1MB blocks for now.






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