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[185.70.43.16]) by gmr-mx.google.com with ESMTPS id k27-20020a05600c1c9b00b0041489943029si391792wms.1.2024.04.01.15.01.40 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 01 Apr 2024 15:01:40 -0700 (PDT) Received-SPF: pass (google.com: domain of fjahr@protonmail.com designates 185.70.43.16 as permitted sender) client-ip=185.70.43.16; Date: Mon, 01 Apr 2024 22:01:35 +0000 To: Andrew Poelstra From: "'Fabian' via Bitcoin Development Mailing List" Cc: bitcoindev@googlegroups.com Subject: Re: [bitcoindev] The Future of Bitcoin Testnet Message-ID: <06oL-GctrcLb99M_RuOgygXKMjtB_vPLHOCuc-axYrGVy_QBRGPu5wA9C2QXDb7cKIJbJu_t_JKmRrr9FsBORdUPavXPFvOi98p04UQuvuE=@protonmail.com> In-Reply-To: References: Feedback-ID: 5067558:user:proton MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Original-Sender: fjahr@protonmail.com X-Original-Authentication-Results: gmr-mx.google.com; dkim=pass header.i=@protonmail.com header.s=protonmail3 header.b=ncX5+rfn; spf=pass (google.com: domain of fjahr@protonmail.com designates 185.70.43.16 as permitted sender) smtp.mailfrom=fjahr@protonmail.com; dmarc=pass (p=QUARANTINE sp=QUARANTINE dis=NONE) header.from=protonmail.com X-Original-From: Fabian Reply-To: Fabian Precedence: list Mailing-list: list bitcoindev@googlegroups.com; contact bitcoindev+owners@googlegroups.com List-ID: X-Google-Group-Id: 786775582512 List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , X-Spam-Score: -1.0 (-) Hi, removing the special rule and moving to a reduced block interval sounds lik= e a good and simple solution. Another idea: Keep the current exception logic and adapt the difficulty adj= ustment code (`CalculateNextWorkRequired`) to look for the last block that = didn't have difficulty 1 and use that block's difficulty as the basis for t= he new difficulty calculation. It seemed like the most intuitive fix to me = when I looked at the code after reading Jameson's first email (see https://= github.com/bitcoin/bitcoin/pull/29775/commits/9913549637706749f0af5d326f949= bd652cbd5f8). Best, Fabian On Monday, April 1st, 2024 at 4:20 PM, Andrew Poelstra wrote: > On Mon, Apr 01, 2024 at 01:37:59PM +0000, Pieter Wuille wrote: >=20 > > As for using other measures to prevent too large difficulty variations.= .. I'm not sure that's desirable, because it always cuts both ways (nicely = demonstrated by the "allow difficulty 1 rule" on testnet3 backfiring and en= abling block storms!). For applications that actually need very predictable= block rate, there is signet. For others, just the normal mainnet rules are= probably not too terrible. I would be ok with having a somewhat reduced bl= ock interval (say a few days instead of 2 weeks) if that's not deemed to co= mplex to implement across the ecosystem, but I don't think it's that import= ant. >=20 >=20 > I really like this. For my part (rust-bitcoin) this would be as simple > as adding an extra parameter to my blockparams structure. Possibly one > already exists, I'd have to check. >=20 > This would be much easier than the existing situation where we have > special-case logic for testnet the difficulty-1 target. >=20 > It would also limit the amount of bikeshedding possible, since there > aren't too many conflicting goals regarding the retargeting window... > unlike tweaking the existing logic where there's a tradeoff between > "we should make this never happen" and "it should happen often enough > that it doesn't break people's code" and "it should happen if blocks > slow down to like, 1/50th their normal rate even if they are still > technically being produced" and "it shouldn't be possible to trigger > it within the 2-hour timestamp-faking window" etc. And questions > about whether we should fix/redesign the interaction between the reset > rule and the normal difficulty retarget. >=20 >=20 > OTOH, since we already have the special logic, I'd also be happy with > tweaking the existing rule. My specific proposal (after reading Jameson's > post, which has some nice graphs of difficulty) would be >=20 > * increase the reset threshold from 20 minutes to 6 hours, which is > (a) well outside the 2-hour window in which miners can easily fake > timestamps, and (b) will basically never be hit by accident > * increase the reset difficulty from 1 to 1MM, which is an rough lower > bound on the "normal" testnet difficulty seen historically >=20 > Which puts us in the "this rule would never be triggered unless > literally everyone stopped mining" corner of the design space. >=20 >=20 > -- > Andrew Poelstra > Director of Research, Blockstream > Email: apoelstra at wpsoftware.net > Web: https://www.wpsoftware.net/andrew >=20 > The sun is always shining in space > -Justin Lewis-Webster >=20 > -- > You received this message because you are subscribed to the Google Groups= "Bitcoin Development Mailing List" group. > To unsubscribe from this group and stop receiving emails from it, send an= email to bitcoindev+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgi= d/bitcoindev/ZgrCxWxMkiAt2Tg2%40camus. --=20 You received this message because you are subscribed to the Google Groups "= Bitcoin Development Mailing List" group. 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