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 ) id 1YuER7-0008Hb-IB for bitcoin-development@lists.sourceforge.net; Mon, 18 May 2015 06:22:01 +0000 Received-SPF: pass (sog-mx-2.v43.ch3.sourceforge.com: domain of ozlabs.org designates 103.22.144.67 as permitted sender) client-ip=103.22.144.67; envelope-from=rusty@ozlabs.org; helo=ozlabs.org; Received: from ozlabs.org ([103.22.144.67]) by sog-mx-2.v43.ch3.sourceforge.com with esmtps (TLSv1:AES256-SHA:256) (Exim 4.76) id 1YuER6-00025l-B2 for bitcoin-development@lists.sourceforge.net; Mon, 18 May 2015 06:22:01 +0000 Received: by ozlabs.org (Postfix, from userid 1011) id 6A126140D18; Mon, 18 May 2015 16:21:52 +1000 (AEST) From: Rusty Russell To: Tier Nolan In-Reply-To: References: <16096345.A1MpJQQkRW@crushinator> <87a8x5l6bt.fsf@rustcorp.com.au> User-Agent: Notmuch/0.17 (http://notmuchmail.org) Emacs/24.4.1 (x86_64-pc-linux-gnu) Date: Mon, 18 May 2015 11:12:11 +0930 Message-ID: <878ucmslu4.fsf@rustcorp.com.au> MIME-Version: 1.0 Content-Type: text/plain X-Spam-Score: -0.6 (/) X-Spam-Report: Spam Filtering performed by mx.sourceforge.net. See http://spamassassin.org/tag/ for more details. -1.5 SPF_CHECK_PASS SPF reports sender host as permitted sender for sender-domain -0.0 SPF_HELO_PASS SPF: HELO matches SPF record -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.0 SPF_PASS SPF: sender matches SPF record 1.1 DATE_IN_PAST_03_06 Date: is 3 to 6 hours before Received: date -0.2 AWL AWL: Adjusted score from AWL reputation of From: address X-Headers-End: 1YuER6-00025l-B2 Cc: Bitcoin Development Subject: Re: [Bitcoin-development] Proposed alternatives to the 20MB step function X-BeenThere: bitcoin-development@lists.sourceforge.net X-Mailman-Version: 2.1.9 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 18 May 2015 06:22:01 -0000 Tier Nolan writes: > On Sat, May 16, 2015 at 1:22 AM, Rusty Russell > wrote: >> 3) ... or maybe not, if any consumed UTXO was generated before the soft >> fork (reducing Tier's perverse incentive). > > The incentive problem can be fixed by excluding UTXOs from blocks before a > certain count. > > UTXOs in blocks before 375000 don't count. OK. Be nice if these were cleaned up, but I guess it's a sunk cost. >> 4) How do we measure UTXO size? There are some constant-ish things in >> there (eg. txid as key, height, outnum, amount). Maybe just add 32 >> to scriptlen? >> > > They can be stored as a fixed digest. That can be any size, depending on > security requirements. > > Gmaxwell's cost proposal is 3-4 bytes per UTXO change. It isn't > 4*UXTO.size - 3*UTXO.size He said "utxo_created_size" not "utxo_created" so I assumed scriptlen? > It is only a small nudge. With only 10% of the block space to play with it > can't be massive. But you made that number up? The soft cap and hard byte limit are different beasts, so there's no need for soft cost cap < hard byte limit. > This requires that transactions include scriptPubKey information when > broadcasting them. Brilliant! I completely missed that possibility... >> 5) Add a CHECKSIG cost. Naively, since we allow 20,000 CHECKSIGs and >> 1MB blocks, that implies a cost of 50 bytes per CHECKSIG (but counted >> correctly, unlike now). >> >> This last one implies that the initial cost limit would be 2M, but in >> practice probably somewhere in the middle. >> >> tx_cost = 50*num-CHECKSIG >> + tx_bytes >> + 4*utxo_created_size >> - 3*utxo_consumed_size >> >> > A 250 byte transaction with 2 inputs and 2 outputs would have an adjusted >> > size of 252 bytes. >> >> Now cost == 352. > > That is to large a cost for a 10% block change. It could be included in > the block size hard fork though. I don't think so. Again, you're mixing units. > I think have one combined "cost" for > transactions is good. It means much fewer spread out transaction checks. > The code for the cost formula would be in one place. Agreed! Unfortunately there'll always be 2, because we really do want a hard byte limit: it's total tx bytes which brings most concerns about centralization. But ideally it'll be so rarely hit that it can be ~ ignored (and certainly not optimized for). Cheers, Rusty.