From: Anthony Towns <aj@erisian•com.au>
To: bitcoin-dev@lists•linuxfoundation.org
Subject: Re: [bitcoin-dev] Capacity increases for the Bitcoin system.
Date: Tue, 8 Dec 2015 14:58:03 +1000 [thread overview]
Message-ID: <20151208045803.GA1042@sapphire.erisian.com.au> (raw)
In-Reply-To: <20151208024224.GA32631@sapphire.erisian.com.au>
> On Mon, Dec 07, 2015 at 10:02:17PM +0000, Gregory Maxwell wrote:
> > If widely used this proposal gives a 2x capacity increase
> > (more if multisig is widely used),
So from IRC, this doesn't seem quite right -- capacity is constrained as
base_size + witness_size/4 <= 1MB
rather than
base_size <= 1MB and base_size + witness_size <= 4MB
or similar. So if you have a 500B transaction and move 250B into the
witness, you're still using up 250B+250B/4 of the 1MB limit, rather than
just 250B of the 1MB limit.
In particular, if you use as many p2pkh transactions as possible, you'd
have 800kB of base data plus 800kB of witness data, and for a block
filled with 2-of-2 multisig p2sh transactions, you'd hit the limit at
670kB of base data and 1.33MB of witness data.
That would be 1.6MB and 2MB of total actual data if you hit the limits
with real transactions, so it's more like a 1.8x increase for real
transactions afaics, even with substantial use of multisig addresses.
The 4MB consensus limit could only be hit by having a single trivial
transaction using as little base data as possible, then a single huge
4MB witness. So people trying to abuse the system have 4x the blocksize
for 1 block's worth of fees, while people using it as intended only get
1.6x or 2x the blocksize... That seems kinda backwards.
Having a cost function rather than separate limits does make it easier to
build blocks (approximately) optimally, though (ie, just divide the fee by
(base_bytes+witness_bytes/4) and sort). Are there any other benefits?
But afaics, you could just have fixed consensus limits and use the cost
function for building blocks, though? ie sort txs by fee divided by [B +
S*50 + W/3] (where B is base bytes, S is sigops and W is witness bytes)
then just fill up the block until one of the three limits (1MB base,
20k sigops, 3MB witness) is hit?
(Doing a hard fork to make *all* the limits -- base data, witness data,
and sigop count -- part of a single cost function might be a win; I'm
just not seeing the gain in forcing witness data to trade off against
block data when filling blocks is already a 2D knapsack problem)
Cheers,
aj
next prev parent reply other threads:[~2015-12-08 4:58 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-12-07 22:02 Gregory Maxwell
2015-12-07 22:54 ` Bryan Bishop
2015-12-08 2:42 ` Anthony Towns
2015-12-08 4:58 ` Anthony Towns [this message]
2015-12-08 5:21 ` Gregory Maxwell
2015-12-08 6:54 ` Anthony Towns
2016-01-18 12:02 ` Anthony Towns
2016-01-22 9:46 ` Anthony Towns
2015-12-08 11:07 ` Wladimir J. van der Laan
2015-12-08 11:14 ` Jorge Timón
2015-12-08 15:12 ` Gavin Andresen
2015-12-08 15:55 ` Justus Ranvier
2015-12-08 17:41 ` Mark Friedenbach
2015-12-08 18:43 ` Justus Ranvier
2015-12-08 19:08 ` Tier Nolan
2015-12-08 19:31 ` Gregory Maxwell
2015-12-08 23:40 ` Jonathan Toomim
2015-12-08 23:48 ` Luke Dashjr
2015-12-09 0:54 ` Jonathan Toomim
2015-12-08 23:50 ` Jorge Timón
2015-12-09 0:56 ` Jonathan Toomim
2015-12-08 23:59 ` Gregory Maxwell
2015-12-09 0:58 ` Jorge Timón
2015-12-09 1:02 ` Jorge Timón
2015-12-09 1:09 ` Gavin Andresen
2015-12-09 1:31 ` Gregory Maxwell
2015-12-09 4:44 ` Ryan Butler
2015-12-09 6:29 ` Gregory Maxwell
2015-12-09 6:36 ` Ryan Butler
2015-12-09 6:59 ` Mark Friedenbach
2015-12-09 7:17 ` Gregory Maxwell
2015-12-09 7:54 ` Jorge Timón
2015-12-09 8:03 ` Gregory Maxwell
2015-12-09 8:46 ` Mark Friedenbach
2015-12-09 11:08 ` Jorge Timón
2015-12-09 16:40 ` Gavin Andresen
2015-12-11 16:18 ` Jorge Timón
2015-12-11 16:43 ` Gavin Andresen
2015-12-12 5:13 ` digitsu
2015-12-12 15:18 ` Mark Friedenbach
2015-12-14 11:21 ` Jonathan Toomim
2015-12-14 12:44 ` Adam Back
2015-12-09 4:51 ` Anthony Towns
2015-12-09 14:51 ` Chris
[not found] ` <CAPWm=eUomq6SBC0ky0WSs5=_G942vigm4RmgYuq0O-yJ-vqC2A@mail.gmail.com>
[not found] ` <CAPg+sBig9O5+he0PWhTkX5iin14QLz5+eCCu6KfwU=DxntKYtg@mail.gmail.com>
2015-12-21 4:33 ` Pieter Wuille
2015-12-21 4:42 ` Justus Ranvier
2015-12-21 4:44 ` Alex Morcos
2015-12-21 4:50 ` Mark Friedenbach
2015-12-21 5:29 ` Douglas Roark
2015-12-21 5:21 ` Btc Drak
2015-12-21 8:07 ` Anthony Towns
2015-12-21 9:56 ` Jorge Timón
2015-12-08 23:48 ` Jonathan Toomim
2015-12-09 0:23 ` Gregory Maxwell
[not found] ` <CAAS2fgRP8bLWZoKR9-iJS-2RKTGQQ9NG-LpAfa2BOdcR=GuB_A@mail.gmail.com>
2015-12-09 0:40 ` Jonathan Toomim
2015-12-09 12:28 Daniele Pinna
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151208045803.GA1042@sapphire.erisian.com.au \
--to=aj@erisian$(echo .)com.au \
--cc=bitcoin-dev@lists$(echo .)linuxfoundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox