MIME-Version: 1.0
In-Reply-To: <CAEgR2PEvpEwv=a0syn43negEnvGcoQ8LBxKRp4-JpnxCNORJSg@mail.gmail.com>
References: <CAEgR2PEMPo3veqJat7OAps1DzTSNFJmJiRbkFgYKvYfxqdbUiw@mail.gmail.com>
	<CAEgR2PELB1_s+o0Bj4Kj9vS27eoqP7gV_VS_6QHQtTUAOnMORg@mail.gmail.com>
	<CAEgR2PFpGWxngq=fKGi7CC_d+=5YWzWwbEEsQNEifCuHAAPAHw@mail.gmail.com>
	<CAEgR2PHnrsdaBiDgywvE9amK8_yPE_hBo0yYOYwUk4T8n7wnAQ@mail.gmail.com>
	<CAEgR2PEgPkRe76hW0Jj7_Z1EdmmNTpTAOKGm_of2dG=XXUOtnA@mail.gmail.com>
	<CAEgR2PHew+fcJWnAt+t8umcwKu4TkshH=AFJ-8MeYysud2MkBQ@mail.gmail.com>
	<CAEgR2PEVwt_shiqwGjK6dPscRUTHayis0PaQO5Dj_fVEGGgaCQ@mail.gmail.com>
	<CAEgR2PEvpEwv=a0syn43negEnvGcoQ8LBxKRp4-JpnxCNORJSg@mail.gmail.com>
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Sat, 10 Dec 2016 09:39:57 -0800
Message-ID: <CAPg+sBiZmRdLOgG9iN2hOWVr_eCLTwDrbuETd_w9-bUJOfTjgw@mail.gmail.com>
To: Daniele Pinna <daniele.pinna@gmail.com>, 
	Bitcoin Protocol Discussion <bitcoin-dev@lists.linuxfoundation.org>
Content-Type: multipart/alternative; boundary=94eb2c124644009c960543515c81
Subject: Re: [bitcoin-dev] Managing block size the same way we do difficulty
 (aka Block75)
Precedence: list

--94eb2c124644009c960543515c81
Content-Type: text/plain; charset=UTF-8

On Sat, Dec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org> wrote:

> We have models for estimating the probability that a block is orphaned
> given average network bandwidth and block size.
>
> The question is, do we have objective measures of these two quantities?
> Couldn't we target an orphan_rate < max_rate?
>

Models can predict orphan rate given block size and network/hashrate
topology, but you can't control the topology (and things like FIBRE hide
the effect of block size on this as well). The result is that if you're
purely optimizing for minimal orphan rate, you can end up with a single
(conglomerate of) pools producing all the blocks. Such a setup has no
propagation delay at all, and as a result can always achieve 0 orphans.

Cheers,

-- 
Pieter

--94eb2c124644009c960543515c81
Content-Type: text/html; charset=UTF-8
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr">On Sat, Dec 10, 2016 at 4:23 AM, Daniele Pinna via bitcoin=
-dev <span dir=3D"ltr">&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfoundat=
ion.org" target=3D"_blank">bitcoin-dev@lists.<wbr>linuxfoundation.org</a>&g=
t;</span> wrote:<br><div class=3D"gmail_extra"><div class=3D"gmail_quote"><=
blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px=
 #ccc solid;padding-left:1ex"><div dir=3D"auto"><div dir=3D"auto"><span sty=
le=3D"font-size:13.696px;font-family:sans-serif">We have models for estimat=
ing the probability that a block is orphaned given average network bandwidt=
h and block size.=C2=A0</span><br></div><div dir=3D"auto"><span style=3D"fo=
nt-size:13.696px;font-family:sans-serif"><br></span></div><div dir=3D"auto"=
><span style=3D"font-family:sans-serif;font-size:13.696px">The question is,=
 do we have objective measures of these two quantities? Couldn&#39;t we tar=
get an orphan_rate &lt; max_rate?=C2=A0</span><span style=3D"font-size:13.6=
96px;font-family:sans-serif"><br></span></div></div></blockquote><div><br><=
/div><div>Models can predict orphan rate given block size and network/hashr=
ate topology, but you can&#39;t control the topology (and things like FIBRE=
 hide the effect of block size on this as well). The result is that if you&=
#39;re purely optimizing for minimal orphan rate, you can end up with a sin=
gle (conglomerate of) pools producing all the blocks. Such a setup has no p=
ropagation delay at all, and as a result can always achieve 0 orphans.<br><=
br></div><div>Cheers,<br><br>-- <br></div><div>Pieter<br><br></div></div></=
div></div>

--94eb2c124644009c960543515c81--