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h=From:From:To:To:Subject:Subject:Date:Date:Message-ID:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To:Cc; bh=eHBkkMLlI2amYNJKiS5et8a1i9rw3Q0KBeoVV7Bl470=; b=bgvCdALblskHcNwjfSdfbkS0YTAdtjN6yGYskpaP20BrigVULoY6/z+zcPLNOJ11 FTfI4pPZjNowNgWxGwKCzVlFtPWrVzYwqh8lBVz6bgdYKjd7BkoOosNy5zZOb5kt5Ka pEYeUzLXsv7NWr+yWGAT5KdGMzsJuTz/UIF7+DPc= Received: from localhost (147.99.27.198 [147.99.27.198]) by mx.zohomail.com with SMTPS id 1699609277623417.4433430499016; Fri, 10 Nov 2023 01:41:17 -0800 (PST) User-agent: mu4e 1.10.7; emacs 29.1 From: Ricardo Wurmus To: guix-devel Subject: Building and caching old Guix derivations for a faster time machine Date: Fri, 10 Nov 2023 10:29:28 +0100 Message-ID: <87o7g29c94.fsf@elephly.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-ZohoMailClient: External Received-SPF: pass client-ip=136.143.184.59; envelope-from=rekado@elephly.net; helo=sender3-of-o59.zoho.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: guix-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+larch=yhetil.org@gnu.org Sender: guix-devel-bounces+larch=yhetil.org@gnu.org X-Migadu-Flow: FLOW_IN X-Migadu-Country: US X-Migadu-Spam-Score: -7.07 X-Spam-Score: -7.07 X-Migadu-Queue-Id: A60FE5D112 X-Migadu-Scanner: mx13.migadu.com X-TUID: R9S/V50SkUdK Hi Guix, to me the biggest downside of using =E2=80=9Cguix time-machine=E2=80=9D is = that it has to do a lot of boring work before the interesting work begins. The boring work includes building Guix derivations for the given channels, most of which have long been collected as garbage on ci.guix.gnu.org. It would be helpful, I think, to more aggressively cache these derivations and their outputs, and to go back in time and build the derivatinons for past revisions of Guix. I would expect there to be a lot of overlap in the produced files, so perhaps it won=E2=80=99t cost all = that much in terms of storage. What do you think? --=20 Ricardo