1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
|
Received: from sog-mx-2.v43.ch3.sourceforge.com ([172.29.43.192]
helo=mx.sourceforge.net)
by sfs-ml-4.v29.ch3.sourceforge.com with esmtp (Exim 4.76)
(envelope-from <tomh@thinlink.com>) id 1Z1l3a-0003fw-9h
for bitcoin-development@lists.sourceforge.net;
Mon, 08 Jun 2015 00:36:50 +0000
X-ACL-Warn:
Received: from mail-qc0-f176.google.com ([209.85.216.176])
by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:RC4-SHA:128)
(Exim 4.76) id 1Z1l3X-0005kU-G4
for bitcoin-development@lists.sourceforge.net;
Mon, 08 Jun 2015 00:36:50 +0000
Received: by qcnj1 with SMTP id j1so19334391qcn.0
for <bitcoin-development@lists.sourceforge.net>;
Sun, 07 Jun 2015 17:36:42 -0700 (PDT)
X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed;
d=1e100.net; s=20130820;
h=x-gm-message-state:message-id:date:from:user-agent:mime-version:to
:subject:content-type:content-transfer-encoding;
bh=15g/sy/yyHgDfbUdvwmz8f6EEZxAcSX9Uds5g2RPuHQ=;
b=aI0k3jzwT1Rg77px8utIfwqrhqaDkCU2mZqTOR4YdItpjFV7fkAbb/YA4vzDp5Gz2y
CHLT7dXQDaxkHmk7ynQzRerPVWOxWfTmYsfWUXuF9t1/W6EXzoYYcLdTvY87I8jZ7f0x
O3bRkuB+Ba+I3CenPqNlv1RAObakFnBOmtYwUpfMUi2ihEjbQp0rofJhmU9sHTOdMGOq
0ATmLIjMMn/PBmYdSH5EkuuKNnPRaCp0YSAKQ1KHPnDZOKLpmuhvZQ5dBRTWW+lhpaHp
tTVg5Jsjd7M01RfnNcc5kPdJ6mJUfR+M0v7CY7aP57VMnTOVlN/B05wgd65/11sBJPAY
O6NA==
X-Gm-Message-State: ALoCoQkvNHYeoprFfUvwq/VyBObhJNBmrQoFBam29+Tsr0ydGXu7IPeVqGSzEOsYiawihmRuT6kd
X-Received: by 10.140.202.130 with SMTP id x124mr17577545qha.9.1433723802007;
Sun, 07 Jun 2015 17:36:42 -0700 (PDT)
Received: from [192.168.1.89] (99-8-65-117.lightspeed.davlca.sbcglobal.net.
[99.8.65.117])
by mx.google.com with ESMTPSA id b85sm523449qkb.8.2015.06.07.17.36.40
for <bitcoin-development@lists.sourceforge.net>
(version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
Sun, 07 Jun 2015 17:36:41 -0700 (PDT)
Message-ID: <5574E39C.3090904@thinlink.com>
Date: Sun, 07 Jun 2015 17:36:44 -0700
From: Tom Harding <tomh@thinlink.com>
User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64;
rv:31.0) Gecko/20100101 Thunderbird/31.7.0
MIME-Version: 1.0
To: Bitcoin Dev <bitcoin-development@lists.sourceforge.net>
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
X-Spam-Score: 0.0 (/)
X-Spam-Report: Spam Filtering performed by mx.sourceforge.net.
See http://spamassassin.org/tag/ for more details.
X-Headers-End: 1Z1l3X-0005kU-G4
Subject: [Bitcoin-development] Block Size Experiment Underway
X-BeenThere: bitcoin-development@lists.sourceforge.net
X-Mailman-Version: 2.1.9
Precedence: list
List-Id: <bitcoin-development.lists.sourceforge.net>
List-Unsubscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=unsubscribe>
List-Archive: <http://sourceforge.net/mailarchive/forum.php?forum_name=bitcoin-development>
List-Post: <mailto:bitcoin-development@lists.sourceforge.net>
List-Help: <mailto:bitcoin-development-request@lists.sourceforge.net?subject=help>
List-Subscribe: <https://lists.sourceforge.net/lists/listinfo/bitcoin-development>,
<mailto:bitcoin-development-request@lists.sourceforge.net?subject=subscribe>
X-List-Received-Date: Mon, 08 Jun 2015 00:36:50 -0000
In September, 2014, a collective experiment began in the bitcoin
ecosystem. Available block space (1MB) began to sometimes fall short of
the space required to mine all of the transactions that would otherwise
have been included.
This chart, posted earlier, shows the onset of the
some-blocks-at-maximum era. http://i.imgur.com/5Gfh9CW.png
Although the average block is only about 400K, real blocks are bigger or
smaller due to the random length of time between blocks (and other
factors). I look at how often this is predicted to happen.
Recently, transactions have been confirmed at a rate of about
100000/day*. The average transaction size for the past 6000 blocks has
been 545 bytes. Using these values,
txesPerMinute =3D 100000 / 24 / 60 =3D 69.4
txesInMaxBlock =3D 999977 / 545 =3D 1834
minutesToFillBlock =3D txesInMaxBlock/txesPerMinute =3D 26.4
Using the theoretical formula for the time before an inter-block
interval of at least a given length **
blockChickenMinutes[x] :=3D 10 (exp(x/10) - x/10 - 1)
we obtain
minutesBetweenFullBlocks =3D blockChickenMinutes[minutesToFillBlock] =3D =
104
We currently expect a maximum-size block every 1 hour + 44 minutes, on
average. If the transaction rate doubles, we should expect a
maximum-size block every 14 minutes, on average. The non-linearity
makes sense, because doubling the average without raising the maximum
requires disproportionately more maximum-size blocks.
This estimate is understated because transaction size and submission
rate have their own distributions. Using the averages of 545 bytes and
100000/day ignores the fact that for some blocks, there are unusually
big and/or numerous transactions, which increases the block size
variance and causes blocks over the threshold to be encountered more
frequently.
These calculations are confirmed by empirical observation of the most
recent 6000 blocks:
http://i.imgur.com/0pQUsdl.png
In many cases, the miner chose to create a 750KB block, which is
unusually likely to be followed by another 750KB or 1MB block, because
the next interval starts off with a 250KB backlog. Some backlog
transactions may experience more than 1 block delay in these cases.
* https://www.quandl.com/data/BCHAIN/NTRAN-Bitcoin-Number-of-Transactions=
** This is a chicken-crossing-the-road problem. Wait time =3D (exp(=CE=BB=
x) =E2=88=92
=CE=BBx - 1) / =CE=BB
Some discussion at
https://github.com/nanotube/supybot-bitcoin-marketmonitor/pull/68.
|
