Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 252A3E31 for ; Sat, 19 Dec 2015 07:51:03 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-ig0-f175.google.com (mail-ig0-f175.google.com [209.85.213.175]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 43C87FC for ; Sat, 19 Dec 2015 07:51:01 +0000 (UTC) Received: by mail-ig0-f175.google.com with SMTP id jw2so6940607igc.1 for ; Fri, 18 Dec 2015 23:51:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=friedenbach-org.20150623.gappssmtp.com; s=20150623; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=3GeNL0WVmr/NF9H3rLDAEIcxTyAVXglqKwG2C3DjiHw=; b=XVk6yRb/ykCqUHdAX3Xwdtwdr2STYqDg0o3rkHC4N2Aq1lEGQMRjhCBorppGaUaUb3 4qbDD/kiUWUlagTN6Aas6UEZCxnSBwJOw8Qe+thN3Go8bq78CYfq1a9BMdaUy1Dfiu3t dMozVIO1QsXYYh7WayDLN7id2SF9ysnAcAEpGpTIB3+eaj8AW4+LpJM801YkIlPbeQiy ZaQDdnW13ldcbUZL4gicIOjcuXOSNfAY5Yfi9XfLMYxqZ+V+Wn6Fb2hHQoAJWCvne10h i7VK6mAcLao92cBqHFA5twgSn8inMCWpES8HP3oxovc0MBXidhlKY3qjmhy3XlmRgDC+ /OuQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc:content-type; bh=3GeNL0WVmr/NF9H3rLDAEIcxTyAVXglqKwG2C3DjiHw=; b=ea/3zGomYFLT2zTAMy//6AwtIKV1DvCOImkId8YWhr7E7YYAgyiQpfBE1wEogNkwE0 PdH3oNvroAHfvKpItYqe1pP4a/rdXXib8gFB0GFQCCdBU9r0pN/OXIJOhD3D84rOB2Gg t5S7YsZCK1X317QFHv3sId5Wsg9k1Ul7zOO9soxUVPzvNzNjRT8rCw+lKDysrvBd78qx GwEaKQSllmPeBWSCZX3rMbcvU3ZDdG5kNqw2dEJEluy0nr1ZDSj2iN9k6rBxWSsM7Qi4 iyQK/qmjcVuFWrT8yTtS0MBsrvLDpXNAlLFDGMG6ooyo1km339LfJNntsvTyIYJCPyz5 VvQg== X-Gm-Message-State: ALoCoQnIzKLRduPxmnJPoA7+2BT1o2O920/iD7PkTj1aI4oa4V59o5dVporhpf1TZKh8iTsTWx7pj3JY61GKoufD6i4rq5aEGg== X-Received: by 10.50.2.105 with SMTP id 9mr7662362igt.40.1450511460706; Fri, 18 Dec 2015 23:51:00 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.132.193 with HTTP; Fri, 18 Dec 2015 23:50:41 -0800 (PST) X-Originating-IP: [49.218.55.28] In-Reply-To: References: <49257841-66C8-4EF7-980B-73DC604CA591@mattcorallo.com> <9869fe48a4fc53fc355a35cead73fca2@xbt.hk> <20151217175541.GA10809@sapphire.erisian.com.au> From: Mark Friedenbach Date: Sat, 19 Dec 2015 15:50:41 +0800 Message-ID: To: "sickpig@gmail.com" Content-Type: multipart/alternative; boundary=089e0115fca05bc59005273b8498 X-Spam-Status: No, score=-2.6 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HTML_MESSAGE,RCVD_IN_DNSWL_LOW autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev , Anthony Towns Subject: Re: [bitcoin-dev] Segregated Witness in the context of Scaling Bitcoin X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Development Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 19 Dec 2015 07:51:03 -0000 --089e0115fca05bc59005273b8498 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Not entirely correct, no. Edge cases also matter. Segwit is described as 4MB because that is the largest possible combined block size that can be constructed. BIP 102 + segwit would allow a maximum relay of 8MB. So you have to be confident that an 8MB relay size would be acceptable, even if a block full of actual transactions would be closer to 3.5MB. On Fri, Dec 18, 2015 at 6:01 PM, sickpig--- via bitcoin-dev < bitcoin-dev@lists.linuxfoundation.org> wrote: > Anthony, > > > On Thu, Dec 17, 2015 at 6:55 PM, Anthony Towns via bitcoin-dev < > bitcoin-dev@lists.linuxfoundation.org> wrote: > >> On Thu, Dec 17, 2015 at 04:51:19PM +0100, sickpig--- via bitcoin-dev >> wrote: >> > On Thu, Dec 17, 2015 at 2:09 PM, Jorge Tim=C3=B3n wrote: >> > > Unless I'm missing something, 2 mb x4 =3D 8mb, so bip102 + SW is alr= eady >> > > equivalent to the 2-4-8 "compromise" proposal [...] >> > isn't SegWit gain ~75%? hence 2mb x 1.75 =3D 3.5. >> >> Segwit as proposed gives a 75% *discount* to witness data with the >> same limit, so at a 1MB limit, that might give you (eg) 2.05MB made up >> of 650kB of base block data plus 1.4MB of witness data; where 650kB + >> 1.4MB/4 =3D 1MB at the 1MB limit; or 4.1MB made up of 1.3MB of base plus >> 2.8MB of witness, for 1.3MB+2.8MB/4 =3D 2MB at a 2MB limit. >> >> > 4x is theoric gain you get in case of 2-2 multisig txs. >> >> With segregated witness, 2-2 multisig transactions are made up of 94B >> of base data, plus about 214B of witness data; discounting the witness >> data by 75% gives 94+214/4=3D148 bytes. That compares to about 301B for >> a 2-2 multisig transaction with P2SH rather than segwit, and 301/148 >> gives about a 2.03x gain, not a 4x gain. A 2.05x gain is what I assumed >> to get the numbers above. >> >> You get further improvements with, eg, 3-of-3 multisig, but to get >> the full, theoretical 4x gain you'd need a fairly degenerate looking >> transaction. >> >> Pay to public key hash with segwit lets you move about half the >> transaction data into the witness, giving about a 1.6x improvement by >> my count (eg 1.6MB =3D 800kB of base data plus 800kB of witness data, >> where 800kB+800kB/4=3D1MB), so I think a gain of between 1.6 and 2.0 is >> a reasonable expectation to have for the proposed segwit scheme overall. >> >> > many thanks for the explanation. > > so it should be fair to say that BIP 102 + SW would bring a gain between > 2*1.6 and 2*2. > > Just for the sake of simplicity if we take the middle of the interval we > could say > that BIP102 + SW will bring us a max block (virtual) size equal to 1MB * = 2 > * 1.8 =3D 3.6 > > Is it right? > > > > > _______________________________________________ > bitcoin-dev mailing list > bitcoin-dev@lists.linuxfoundation.org > https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev > > --089e0115fca05bc59005273b8498 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
Not entirely correct, no. Edge cases also matter. Segwit i= s described as 4MB because that is the largest possible combined block size= that can be constructed. BIP 102 + segwit would allow a maximum relay of 8= MB. So you have to be confident that an 8MB relay size would be acceptable,= even if a block full of actual transactions would be closer to 3.5MB.
<= /div>

On Fri, Dec = 18, 2015 at 6:01 PM, sickpig--- via bitcoin-dev <bitco= in-dev@lists.linuxfoundation.org> wrote:
Anthony,

=

On Thu, Dec 17, 2015 = at 6:55 PM, Anthony Towns via bitcoin-dev <bitcoin-dev= @lists.linuxfoundation.org> wrote:
On Thu, Dec 17, 2015 at 04:51:19PM +0100, sickpig--- via bitcoin-de= v wrote:
> On Thu, Dec 17, 2015 at 2:09 PM, Jorge Tim=C3=B3n wrote:
> > Unless I'm missing something, 2 mb x4 =3D 8mb, so bip102 + SW= is already
> > equivalent to the 2-4-8 "compromise" proposal [.= ..]
> isn't SegWit gain ~75%? hence 2mb x 1.75 =3D 3.5.

Segwit as proposed gives a 75% *discount* to witness data with the same limit, so at a 1MB limit, that might give you (eg) 2.05MB made up
of 650kB of base block data plus 1.4MB of witness data; where 650kB +
1.4MB/4 =3D 1MB at the 1MB limit; or 4.1MB made up of 1.3MB of base plus 2.8MB of witness, for 1.3MB+2.8MB/4 =3D 2MB at a 2MB limit.

> 4x is theoric gain you get in case of 2-2 multisig txs.

With segregated witness, 2-2 multisig transactions are made up of 94= B
of base data, plus about 214B of witness data; discounting the witness
data by 75% gives 94+214/4=3D148 bytes. That compares to about 301B for
a 2-2 multisig transaction with P2SH rather than segwit, and 301/148
gives about a 2.03x gain, not a 4x gain. A 2.05x gain is what I assumed
to get the numbers above.

You get further improvements with, eg, 3-of-3 multisig, but to get
the full, theoretical 4x gain you'd need a fairly degenerate looking transaction.

Pay to public key hash with segwit lets you move about half the
transaction data into the witness, giving about a 1.6x improvement by
my count (eg 1.6MB =3D 800kB of base data plus 800kB of witness data,
where 800kB+800kB/4=3D1MB), so I think a gain of between 1.6 and 2.0 is
a reasonable expectation to have for the proposed segwit scheme overall.

many thanks for the explanation.
so it should be fair to say that BIP = 102 + SW would bring a gain between 2*1.6 and 2*2.

Just for the sake of simplicity if we take the middle of t= he interval we could say
that BIP102 += SW will bring us a max block (virtual) size equal to 1MB * 2 * 1.8 =3D 3.6=

Is it right?




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