Re: [bitcoin-dev] Three hardfork-related BIPs

From: Andrew Johnson <andrew.johnson83@gmail•com>
To: Bitcoin Dev <bitcoin-dev@lists•linuxfoundation.org>,
	 Christian Decker <decker.christian@gmail•com>
Subject: Re: [bitcoin-dev] Three hardfork-related BIPs
Date: Fri, 27 Jan 2017 17:53:02 -0600	[thread overview]
Message-ID: <CAAy62_KUSNTjivwJT87K9f1c=k-6gdaLXEBJjcy2KK+uLSTWDA@mail.gmail.com> (raw)
In-Reply-To: <20170127212810.GA5856@nex>

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Thanks for replying, I'd be interested to see what you would come up with
today using the same methodology, seeing as max single hard drive capacity
has roughly doubled, global average internet bandwidth has increased 31%
from 4.8Mbps to 6.3Mbps(sourced from Akamai State of the Internet reports
2014q4 and 2016q3), and we now have xThin and compact blocks to help
significantly with block propagation time.  Not to mention the usual
improvements in CPUs(not that we're anywhere near a CPU bottleneck today
anyway save for quadratic hashing when raising the blocksize, but I don't
think that anyone would seriously suggest an increase without addressing
that).

I don't think that the 17% yearly increase is too far off base considering
current global trends(although I still don't particularly like the idea of
centrally planning the limit, especially not that far into the future), but
the 66% decrease first seems completely out of touch with reality.

I'd also like to point out to Luke that Satoshi envisioned most full nodes
running in data centers in the white paper, not every single user needs to
run a full node to use bitcoin.  Not to present this as an argument from
authority, but rather to remind us what the intention of the system was to
be(p2p cash, not a settlement layer only afforded by the wealthiest and
largest value transactions).  That a lot of people want to continue to move
in that direction shouldn't be a surprise.

On Jan 27, 2017 3:28 PM, "Christian Decker via bitcoin-dev" <
bitcoin-dev@lists•linuxfoundation.org> wrote:

On Fri, Jan 27, 2017 at 03:47:20PM -0500, Greg Sanders via bitcoin-dev
wrote:
> Note that the 4MB number comes from a single network metric.
>
> Quotes directly from the paper in question:
> http://fc16.ifca.ai/bitcoin/papers/CDE+16.pdf
>
> >Our results hinge on the key metric of effective throughput in the
overlay
> network, which we define here as which blocks propagate within an average
> block interval period the percentage of nodes to.
> ...
> >Note that as we consider only a subset of possible metrics (due to
> difficulty in accurately measuring others), our results on
> reparametrization may be viewed as upper bounds: additional metrics could
> reveal even stricter limits.
>
> It says nothing about any mining centralization pressure, DoS attacks,
etc.
> A single metric among many we have to contend with.
>

As one of the authors of that paper and the source of the measurement
data I'd also like to point out that the 4MB number is indeed intended
as an optimistic upper bound on todays network capacity.

More importantly it's not a black and white situation, where there is
a magic number beyond which Bad Things (TM) happen, it's a spectrum on
which we can see a few threshold beyond which we _know_ Bad Things
definitely happen. Miner centralization pressure is felt earlier.
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