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 3396ABC0 for ; Wed, 5 Dec 2018 14:09:08 +0000 (UTC) X-Greylist: whitelisted by SQLgrey-1.7.6 Received: from mail-vs1-f47.google.com (mail-vs1-f47.google.com [209.85.217.47]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id D0476815 for ; Wed, 5 Dec 2018 14:09:07 +0000 (UTC) Received: by mail-vs1-f47.google.com with SMTP id p74so12147868vsc.0 for ; Wed, 05 Dec 2018 06:09:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to; bh=DayG8XAklaIgB1wf/3qrdqkuvg6pFzuRJqhNq80aaYI=; b=ICx9eSVG42FIk9BWGaG5E0MaKKs4MO7uQM6SImQpJrohdYqVgofY3x+CtlgqF0Qtna 5K88jBksEk7l5jxRO9QaJMWC9b8mZ/G5NtSHm505xfbnkJX8owG9RRqlvucPClQmjhpo +B1qPCoWxusdqOoEj/mhkIRA58Tx0yDkDsDMo1+LJq6LfzGxdx6CTcWsWrzW7pUUBc8s hDwKfgaZOf2jYNvSXsq7W7WmYv2UgkJhD8C4YdsnOqhQ0b5SWIy2pAIQQucWaGKuFq2r gsb9DUv6Fvhy+eQfBpWFaqzVyQaE/J7S8z2mAA7JdBM6tWtIdiBIytvOHuMB+kEId8TZ qAhQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to; bh=DayG8XAklaIgB1wf/3qrdqkuvg6pFzuRJqhNq80aaYI=; b=IPd1FHWinaupE1dkBomYGavijum5A2hn6QbcKEY4nLPHW6Cfmf3UyRUx9f7DwT1dGN mWyMhEOlmUCE+ysEN6xmIyXilSoARTcepuA4+hKsL+f73kVLb/HciTNY+ZNYe00o4NkA m2sMHFVN5fSRsfsFpHoP1C3ZJvYynNjNk66t+OIdjSdLPE5dvwFeJJtmKqVjR0HOlScf uG+xOQDfgv4TRx9/qvknrZ9M5e8l4UN6wfvqwzUXP9/ha2mtoB9tSmoO5tghnc8/fodd h4lYP/xLCIhs++7K7oEtu64svGCFmCxKEESV8z+KT9ssWNPs8rgU3cBuj1JBGbK9TJj0 lvEQ== X-Gm-Message-State: AA+aEWaXQMxaxd5IZ1FYCGu1SKhElkPY4BgfahKPwtEuifE2Yo22BW1z UGNmlIajxPn0bxTFqlljN4fvC+3SmQ4AcgyIRqGVdhXJ X-Google-Smtp-Source: AFSGD/XoXPNlAV0r4rv/O7h+CF9zGwtBxwy3xPvbuMcumpwtm4B4T8SB1mNuyBj3JPhhHt5kwPG8OooW0eEx7xO9jxc= X-Received: by 2002:a67:46c8:: with SMTP id a69mr10875442vsg.45.1544018946565; Wed, 05 Dec 2018 06:09:06 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Zawy Date: Wed, 5 Dec 2018 09:08:56 -0500 Message-ID: To: Dave Scotese , Bitcoin Protocol Discussion Content-Type: text/plain; charset="UTF-8" X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, FREEMAIL_FROM, RCVD_IN_DNSWL_NONE autolearn=ham version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.linux-foundation.org X-Mailman-Approved-At: Mon, 10 Dec 2018 17:30:30 +0000 Subject: Re: [bitcoin-dev] How much is too much time between difficulty changes? X-BeenThere: bitcoin-dev@lists.linuxfoundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Bitcoin Protocol Discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 05 Dec 2018 14:09:08 -0000 It's possible to let the difficulty linearly drop as the solvetime goes beyond some limit (credit AS). If the limit is greater than any delay in the past it could be backwards-compatible. A simple daily-rolling average DA like BCH is probably the best option if a faster DA is ever needed. As a point of research interest (not likely to be needed by BTC), I've taken the first above idea of "intra-block" timestamp-based difficulty adjustment to the limit and made it symmetrical (higher D for fast solves) and continuous. The result is a "tightening of the Poisson" that increases "availability" (predictable solution times) at an expense in "consistency" (orphans). It requires a very tight future time limit to reduce timestamp manipulation. My objective was to help small coins deal with persistent 20x hash rate changes that result in long delays. About 3 coins have it on testnet. https://github.com/zawy12/difficulty-algorithms/issues/36