Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 4D843F90 for ; Thu, 3 Sep 2015 14:31:33 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-wi0-f177.google.com (mail-wi0-f177.google.com [209.85.212.177]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id A863D19F for ; Thu, 3 Sep 2015 14:31:32 +0000 (UTC) Received: by wibz8 with SMTP id z8so101165482wib.1 for ; Thu, 03 Sep 2015 07:31:31 -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=8Q/pW7fMPKfO2z+pKUP1T5AmOg8PptAbWIJlyTYEGX0=; b=vhVncPoFbbz74e+J4n1UbaJXraxJJO3niPJv5UAjd4r0cmYJb2Uhmq66m2MvR7QtAt 5zrFzKEsiswbWRaj2O0fCm97uE4YtKsz+ZLG7AzIgnL/+uLAgyrmSq8gtd537wDfwah3 jvO2kM//QwR/Jb3QiNkVVA4K6SuYN/siQFRIv7+R+Kqm4uCH7oZgjiIDS6lG+R7IXWRm yKSw3ACEdYuxoVzW9RCQ1Av29nWGiA/TrccD5JQhpIKtkUu21B2oQPmJV2c5LHWasIdc LLi7FcePNjvzMwE8LJ9tw7JGDjA4odQzXIyel+cZKd4kmh8bi119OeVZ1A/neTPcldZl xmkA== MIME-Version: 1.0 X-Received: by 10.180.92.138 with SMTP id cm10mr14726162wib.33.1441290691413; Thu, 03 Sep 2015 07:31:31 -0700 (PDT) Received: by 10.28.15.11 with HTTP; Thu, 3 Sep 2015 07:31:31 -0700 (PDT) In-Reply-To: References: Date: Thu, 3 Sep 2015 10:31:31 -0400 Message-ID: From: Jeff Garzik To: Gregory Maxwell Content-Type: multipart/alternative; boundary=f46d043be24eae0bc5051ed8a3f3 X-Spam-Status: No, score=-2.7 required=5.0 tests=BAYES_00,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 Cc: Bitcoin development mailing list Subject: Re: [bitcoin-dev] block size - pay with difficulty 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 14:31:33 -0000 --f46d043be24eae0bc5051ed8a3f3 Content-Type: text/plain; charset=UTF-8 It's written as 'a' and/or 'b'. If you don't have idle hashpower, then paying with difficulty requires some amount of collusion ('a') Any miner paying with a higher difficulty either needs idle hashpower, or self-increase their own difficulty at the possible *opportunity cost* of losing an entire block's income to another miner who doesn't care about changing the block size. The potential loss does not economically compensate for size increase gains in most cases, when you consider the variability of blocks (they come in bursts and pauses) and the fee income that would be associated. Miners have more to lose paying with diff than they gain -- unless the entire network colludes out-of-band with ~90% certainty, by collectively agreeing to increase the block period by collectively agreeing with pay-with-diff until the globally desired block size is reached. At that level of collusion, we can create far more simple schemes to increase block size. Pay-with-diff will either not get used, or lead to radical short term block size (and thus fee) volatility. It is complex & difficult for all players to reason, and a Rational game theory choice can be to avoid paying-for-diff even when the network desperately needs an upgrade. On Thu, Sep 3, 2015 at 2:57 AM, Gregory Maxwell wrote: > On Thu, Sep 3, 2015 at 4:05 AM, Jeff Garzik via bitcoin-dev > wrote: > > (b) requiring miners to have idle > > hashpower on hand to change block size are both unrealistic and > potentially > > I really cannot figure out how you could characterize pay with > difficty has in any way involving idle hashpower. > > Can you walk me through this? > --f46d043be24eae0bc5051ed8a3f3 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
It's written as 'a' and/or 'b'.=C2=A0 = If you don't have idle hashpower, then paying with difficulty requires = some amount of collusion ('a') =C2=A0

Any miner paying= with a higher difficulty either needs idle hashpower, or self-increase the= ir own difficulty at the possible opportunity cost of losing an enti= re block's income to another miner who doesn't care about changing = the block size.=C2=A0 The potential loss does not economically compensate f= or size increase gains in most cases, when you consider the variability of = blocks (they come in bursts and pauses) and the fee income that would be as= sociated.

Miners have more to lose paying with dif= f than they gain -- unless the entire network colludes out-of-band with ~90= % certainty, by collectively agreeing to increase the block period by colle= ctively agreeing with pay-with-diff until the globally desired block size i= s reached.=C2=A0 At that level of collusion, we can create far more simple = schemes to increase block size.

Pay-with-diff will= either not get used, or lead to radical short term block size (and thus fe= e) volatility.=C2=A0 It is complex & difficult for all players to reaso= n, and a Rational game theory choice can be to avoid paying-for-diff even w= hen the network desperately needs an upgrade.


=




On Thu, Sep 3, 2015 at 2:57= AM, Gregory Maxwell <gmaxwell@gmail.com> wrote:
On Thu, Sep 3, 2015 at 4:05 AM, Je= ff Garzik via bitcoin-dev
<bitcoin-dev@li= sts.linuxfoundation.org> wrote:
> (b) requiring miners to have idle
> hashpower on hand to change block size are both unrealistic and potent= ially

I really cannot figure out how you could characterize pay with
difficty has in any way involving idle hashpower.

Can you walk me through this?

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