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Date: Thu, 23 Jul 2015 21:56:36 +0200
Message-ID: <CAAUq485RqbNpBa6i34H517Oo4+MHkT683inwU-sMX3Y=vBTwqg@mail.gmail.com>
From: Marcel Jamin <marcel@jamin.net>
To: Peter Todd <pete@petertodd.org>
Content-Type: multipart/alternative; boundary=001a1141e5f2f63297051b904820
Cc: slurms--- via bitcoin-dev <bitcoin-dev@lists.linuxfoundation.org>
Subject: Re: [bitcoin-dev] Bitcoin Node Speed Test
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He measured the upload capacity of the peers by downloading from them, or
am I being dumb? :)


2015-07-23 18:05 GMT+02:00 Peter Todd via bitcoin-dev <
bitcoin-dev@lists.linuxfoundation.org>:

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> Hash: SHA256
>
>
>
> On 23 July 2015 10:19:59 GMT-04:00, slurms--- via bitcoin-dev <
> bitcoin-dev@lists.linuxfoundation.org> wrote:
> >This does not support the theory that the network has the available
> >bandwidth for increased block sizes, as in its current state 37% of
> >nodes would fail to upload a 20MB block to a single peer in under 20
> >seconds (referencing a number quoted by Gavin). If the bar for
> >suitability is placed at taking only 1% of the block time (6 seconds)
> >to upload one block to one peer, then 69% of the network fails for 20MB
> >blocks. For comparison, only 10% fail this metric for 1MB blocks.
>
> Note how due to bandwidth being generally asymetric your findings are
> probably optimistic - you've measured download capacity. On top of that
> upload is further reduced by the fact that multiple peers at once need to
> be sent blocks for reliability.
>
> Secondly you're measuring a network that isn't under attack - we need
> significant additional margin to resist attack as performance is
> consensus-critical.
>
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> _______________________________________________
> bitcoin-dev mailing list
> bitcoin-dev@lists.linuxfoundation.org
> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev
>

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<div dir=3D"ltr">He measured the upload capacity of the peers by downloadin=
g from them, or am I being dumb? :)<div><br><div class=3D"gmail_extra"><br>=
<div class=3D"gmail_quote">2015-07-23 18:05 GMT+02:00 Peter Todd via bitcoi=
n-dev <span dir=3D"ltr">&lt;<a href=3D"mailto:bitcoin-dev@lists.linuxfounda=
tion.org" target=3D"_blank">bitcoin-dev@lists.linuxfoundation.org</a>&gt;</=
span>:<br><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex">-----BEGIN PGP SIGNED MESSAGE-----=
<br>
Hash: SHA256<br>
<span class=3D""><br>
<br>
<br>
On 23 July 2015 10:19:59 GMT-04:00, slurms--- via bitcoin-dev &lt;<a href=
=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.linuxfo=
undation.org</a>&gt; wrote:<br>
&gt;This does not support the theory that the network has the available<br>
&gt;bandwidth for increased block sizes, as in its current state 37% of<br>
&gt;nodes would fail to upload a 20MB block to a single peer in under 20<br=
>
&gt;seconds (referencing a number quoted by Gavin). If the bar for<br>
&gt;suitability is placed at taking only 1% of the block time (6 seconds)<b=
r>
&gt;to upload one block to one peer, then 69% of the network fails for 20MB=
<br>
&gt;blocks. For comparison, only 10% fail this metric for 1MB blocks.<br>
<br>
</span>Note how due to bandwidth being generally asymetric your findings ar=
e probably optimistic - you&#39;ve measured download capacity. On top of th=
at upload is further reduced by the fact that multiple peers at once need t=
o be sent blocks for reliability.<br>
<br>
Secondly you&#39;re measuring a network that isn&#39;t under attack - we ne=
ed significant additional margin to resist attack as performance is consens=
us-critical.<br>
<br>
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<div class=3D"HOEnZb"><div class=3D"h5"><br>
_______________________________________________<br>
bitcoin-dev mailing list<br>
<a href=3D"mailto:bitcoin-dev@lists.linuxfoundation.org">bitcoin-dev@lists.=
linuxfoundation.org</a><br>
<a href=3D"https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev" =
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man/listinfo/bitcoin-dev</a><br>
</div></div></blockquote></div><br></div></div></div>

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