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 5DE35826 for ; Mon, 10 Aug 2015 21:01:07 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f182.google.com (mail-io0-f182.google.com [209.85.223.182]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 3F51D17A for ; Mon, 10 Aug 2015 21:01:06 +0000 (UTC) Received: by iodb91 with SMTP id b91so122733055iod.1 for ; Mon, 10 Aug 2015 14:01:05 -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=Y2zj6Q5FvZ52Wma7HAS++L48H+e+2c8gOpJojXIbY9k=; b=y1lL5fqq7Z1JDrIG4Sd4OFC+gUWOUdDzK928qoFp1GVEPyNgcOY9H/+nNVqxGVfSkS NDyQRFgVsQ+eCWmEw25VjThtW7WFKGHW3kPKCnNX0j9Xv44ZjxBYMyVqkCTXtdsS71l4 RlngxhmfIRwoesLpzZ8XLxOw1KXgTqbEiPx8/DVQRwU0CKNivqdKca9fOC9lZ9ZDw8cz jQWWySOnYBAtTp44w5e25JB1v5oUmHyfEaOi+KNieHe6UYzvHfKKWhpTAIXZUCxhPMWm 6qzLs+KvCQI4xl+CPKzpDsTwqD7rZboZ97zPISZ2cnOq6FIvTxRnmKlZAsVNviTYm1RT 7Ejg== MIME-Version: 1.0 X-Received: by 10.107.37.142 with SMTP id l136mr23656042iol.126.1439240465621; Mon, 10 Aug 2015 14:01:05 -0700 (PDT) Received: by 10.36.77.201 with HTTP; Mon, 10 Aug 2015 14:01:05 -0700 (PDT) Received: by 10.36.77.201 with HTTP; Mon, 10 Aug 2015 14:01:05 -0700 (PDT) In-Reply-To: References: Date: Mon, 10 Aug 2015 23:01:05 +0200 Message-ID: From: Pieter Wuille To: Sergio Demian Lerner Content-Type: multipart/alternative; boundary=001a1140269ab329aa051cfb48e1 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 Dev Subject: Re: [bitcoin-dev] If you had a single chance to double the transactions/second Bitcoin allows... 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: Mon, 10 Aug 2015 21:01:07 -0000 --001a1140269ab329aa051cfb48e1 Content-Type: text/plain; charset=UTF-8 On Aug 7, 2015 11:19 PM, "Sergio Demian Lerner via bitcoin-dev" < bitcoin-dev@lists.linuxfoundation.org> wrote: > b. Reduce the block rate to a half (average 5 minute blocks) > > Suppose this is a one time hard fork. There no drastic technical problems with any of them: "SPV" mining and the relay network has shown that block propagation is not an issue for such as small change. Mining centralization won't radically change for a 2x adjustment. I don't understand this. All problems that result from propagation delay are literally doubled by doing so. Centralization pressure results from the ratio between propagation time and interblock time. Efficient propagation algorithms like the relay network make this presumably grow sublinear with larger blocks, but changing the interblock time affects it exactly proportionally. All problems that result from propagation delay are literally doubled by doing this. Doubling the block size has a smaller effect. You may argue that these centralization effects are small, but reducing the interblock time has a stronger effect on them than the block size. Also, you seem to consider SPV mining a good thing? It requires trust between miners that know eachother, and fundamentally breaks the security assumption of SPV clients... and if the propagation/interblock ratio was lower, SPV mining would have less effect. I'd say it is exactly a result of the centralization pressure we're trying to avoid. -- Pieter --001a1140269ab329aa051cfb48e1 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable

On Aug 7, 2015 11:19 PM, "Sergio Demian Lerner via bitc= oin-dev" <= bitcoin-dev@lists.linuxfoundation.org> wrote:
> b. Reduce the block rate to a half (average 5 minute blocks)
>
> Suppose this is a one time hard fork. There no drastic technical probl= ems with any of them: "SPV" mining and the relay network has show= n that block propagation is not an issue for such as small change. Mining c= entralization won't radically change for a 2x adjustment.=C2=A0

I don't understand this. All problems that result from p= ropagation delay are literally doubled by doing so. Centralization pressure= results from the ratio between propagation time and interblock time. Effic= ient propagation algorithms like the relay network make this presumably gro= w sublinear with larger blocks, but changing the interblock time affects it= exactly proportionally.

All problems that result from propagation delay are literall= y doubled by doing this. Doubling the block size has a smaller effect. You = may argue that these centralization effects are small, but reducing the int= erblock time has a stronger effect on them than the block size.

Also, you seem to consider SPV mining a good thing? It requi= res trust between miners that know eachother, and fundamentally breaks the = security assumption of SPV clients... and if the propagation/interblock rat= io was lower, SPV mining would have less effect. I'd say it is exactly = a result of the centralization pressure we're trying to avoid.

--
Pieter

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