From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 97A07E1C for ; Fri, 18 Dec 2015 20:15:56 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-io0-f180.google.com (mail-io0-f180.google.com [209.85.223.180]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id 825DA125 for ; Fri, 18 Dec 2015 20:15:55 +0000 (UTC) Received: by mail-io0-f180.google.com with SMTP id o67so101165637iof.3 for ; Fri, 18 Dec 2015 12:15:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=vQw7tSIMDyPFGPKuMhL7+I7Nz2EJgGgaxUA5VhBHoDA=; b=onYpCAAfdnD+em1Cfw7XiC4SaGicpCb9F2SrSLs/SVv5RQRrD4tBu8HufgIIo6KXLR nSgBuk5VHXyPg5aRZCrSmJ9wG2LViTMijl2q6fNJD1/UE5NAdKtdRIBccmo9XTn1KrMX RN1gqpsxdvdvLmkkKHbRL1jxM5nq20ksqhUdWjE+fFvIoubuefwg2QJ2D0fyMqbMuh3Y vE7NF0qGp3lYolEoNPJ9EBjbqsWPe+S/Q4xU4XXM8//VmpH4PO2YKbTa81y3CvoLI7Ry tkYpy6PTsD0e0cRP8qI1qYTgwIv2loFxgXN0Qnc4Te6YX/OsyoGPTSg8Jk2pFmbpBYsz N0qw== MIME-Version: 1.0 X-Received: by 10.107.46.137 with SMTP id u9mr6870487iou.136.1450469754997; Fri, 18 Dec 2015 12:15:54 -0800 (PST) Received: by 10.79.8.198 with HTTP; Fri, 18 Dec 2015 12:15:54 -0800 (PST) In-Reply-To: References: Date: Fri, 18 Dec 2015 15:15:54 -0500 Message-ID: From: Jeff Garzik To: =?UTF-8?B?Sm9yZ2UgVGltw7Nu?= Content-Type: multipart/alternative; boundary=001a113abfae814966052731ce89 X-Spam-Status: No, score=-1.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, HTML_MESSAGE, RCVD_IN_DNSWL_LOW, URIBL_BLACK autolearn=no version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org Cc: Bitcoin Dev Subject: Re: [bitcoin-dev] The increase of max block size should be determined by block height instead of block time 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: Fri, 18 Dec 2015 20:15:56 -0000 --001a113abfae814966052731ce89 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable My preference is height activation + one step per block (i.e. also height). Height seems KISS. AFAICT most of the attacks would occur around the already-heavily-watched flag day activation event, in a height based environment, a useful attribute. However I would like to hear from others about possible attacks with the various approaches, before diverging from the default community approach of switch-based-on-time. On Fri, Dec 18, 2015 at 3:10 PM, Jorge Tim=C3=B3n wrote: > Well, if it's not going to be height, I think median time of the previous > block is better than the time of the current one, and would also solve Ch= un > Wang's concerns. > But as said I prefer to use heights that correspond to diff recalculation > (because that's the window that bip9 will use for the later 95% > confirmation anyway). > On Dec 18, 2015 9:02 PM, "Jeff Garzik" wrote: > >> From a code standpoint, based off height is easy. >> >> My first internal version triggered on block 406,800 (~May 5), and each >> block increased by 20 bytes thereafter. >> >> It was changed to time, because time was the standard used in years past >> for other changes; MTP flag day is more stable than block height. >> >> It is preferred to have a single flag trigger (height or time), rather >> than the more complex trigger-on-time, increment-on-height, but any >> combination of those will work. >> >> Easy to change code back to height-based... >> >> >> >> On Fri, Dec 18, 2015 at 2:52 PM, Jorge Tim=C3=B3n < >> bitcoin-dev@lists.linuxfoundation.org> wrote: >> >>> I agree that nHeight is the simplest option and is my preference. >>> Another option is to use the median time from the previous block (thus >>> you know whether or not the next block should start the miner confirmat= ion >>> or not). In fact, if we're going to use bip9 for 95% miner upgrade >>> confirmation, it would be nice to always pick a difficulty retarget blo= ck >>> (ie block.nHeight % DifficultyAdjustmentInterval =3D=3D 0). >>> Actually I would always have an initial height in bip9, for softforks >>> too. >>> I would also use the sign bit as the "hardfork bit" that gets activated >>> for the next diff interval after 95% is reached and a hardfork becomes >>> active (that way even SPV nodes will notice when a softfork or hardfor= k >>> happens and also be able to tell which one is it). >>> I should update bip99 with all this. And if the 2 mb bump is >>> uncontroversial, maybe I can add that to the timewarp fix and th recove= ry >>> of the other 2 bits in block.nVersion (given that bip102 doesn't seem t= o >>> follow bip99's recommendations and doesn't want to give 6 full months a= s >>> the pre activation grace period). >>> On Dec 18, 2015 8:17 PM, "Chun Wang via bitcoin-dev" < >>> bitcoin-dev@lists.linuxfoundation.org> wrote: >>> >>>> In many BIPs we have seen, include the latest BIP202, it is the block >>>> time that determine the max block size. From from pool's point of >>>> view, it cannot issue a job with a fixed ntime due to the existence of >>>> ntime roll. It is hard to issue a job with the max block size unknown. >>>> For developers, it is also easier to implement if max block size is a >>>> function of block height instead of time. Block height is also much >>>> more simple and elegant than time. >>>> _______________________________________________ >>>> bitcoin-dev mailing list >>>> bitcoin-dev@lists.linuxfoundation.org >>>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>>> >>> >>> _______________________________________________ >>> bitcoin-dev mailing list >>> bitcoin-dev@lists.linuxfoundation.org >>> https://lists.linuxfoundation.org/mailman/listinfo/bitcoin-dev >>> >>> >> --001a113abfae814966052731ce89 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: quoted-printable
My preference is height activation + one step per block (i= .e. also height).=C2=A0 Height seems KISS.

AFAICT most o= f the attacks would occur around the already-heavily-watched flag day activ= ation event, in a height based environment, a useful attribute.
<= br>
However I would like to hear from others about possible = attacks with the various approaches, before diverging from the default comm= unity approach of switch-based-on-time.


=




On Fri, Dec 18, 2015 at 3:10 PM, Jo= rge Tim=C3=B3n <jtimon@jtimon.cc> wrote:

Well, if it's not going to be height, I th= ink median time of the previous block is better than the time of the curren= t one, and would also solve Chun Wang's concerns.
But as said I prefer to use heights that correspond to diff recalculation (= because that's the window that bip9 will use for the later 95% confirma= tion anyway).

On Dec 18, 2015 9:02 PM, "Jeff Garzik"= <jgarzik@gmail.c= om> wrote:
From a code standpoint, based off height is easy.

My first internal version triggered on block 406,800 (~May 5), and= each block increased by 20 bytes thereafter.

It w= as changed to time, because time was the standard used in years past for ot= her changes; MTP flag day is more stable than block height.

<= /div>
It is preferred to have a single flag trigger (height or time), r= ather than the more complex trigger-on-time, increment-on-height, but any c= ombination of those will work.

Easy to change code= back to height-based...



On Fri, Dec 18, 2015 at 2:= 52 PM, Jorge Tim=C3=B3n <bitcoin-dev@lists.linuxfounda= tion.org> wrote:

I agree that nHeight is the simplest option and is my preference.<= br> Another option is to use the median time from the previous block (thus you = know whether or not the next block should start the miner confirmation or n= ot). In fact, if we're going to use bip9=C2=A0 for 95% miner upgrade co= nfirmation, it would be nice to always pick a difficulty retarget block (ie= block.nHeight % DifficultyAdjustmentInterval =3D=3D 0).
Actually I would always have an initial height in bip9, for softforks too.<= br> I would also use the sign bit as the "hardfork bit" that gets act= ivated for the next diff interval after 95% is reached and a hardfork becom= es active (that way even SPV nodes will notice when a softfork=C2=A0 or har= dfork happens and also be able to tell which one is it).
I should update bip99 with all this. And if the 2 mb bump is uncontroversia= l, maybe I can add that to the timewarp fix and th recovery of the other 2 = bits in block.nVersion (given that bip102 doesn't seem to follow bip99&= #39;s recommendations and doesn't want to give 6 full months as the pre= activation grace period).

On Dec 18, 2015 8:17 PM, "Chun Wang via bit= coin-dev" <bitcoin-dev@lists.linuxfoundation.org> wrote:
In many BIPs we have se= en, include the latest BIP202, it is the block
time that determine the max block size. From from pool's point of
view, it cannot issue a job with a fixed ntime due to the existence of
ntime roll. It is hard to issue a job with the max block size unknown.
For developers, it is also easier to implement if max block size is a
function of block height instead of time. Block height is also much
more simple and elegant than time.
_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev

_______________________________________________
bitcoin-dev mailing list
= bitcoin-dev@lists.linuxfoundation.org
https://lists.linuxfoundation.org/mail= man/listinfo/bitcoin-dev



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