From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI, RCVD_IN_MSPIKE_H3,RCVD_IN_MSPIKE_WL,SPF_HELO_NONE,SPF_NONE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 27D471FD45 for ; Thu, 9 Jan 2020 11:13:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729812AbgAILNP (ORCPT ); Thu, 9 Jan 2020 06:13:15 -0500 Received: from smtp1.de.adit-jv.com ([93.241.18.167]:55191 "EHLO smtp1.de.adit-jv.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728918AbgAILNO (ORCPT ); Thu, 9 Jan 2020 06:13:14 -0500 Received: from localhost (smtp1.de.adit-jv.com [127.0.0.1]) by smtp1.de.adit-jv.com (Postfix) with ESMTP id 2F44A3C04C0; Thu, 9 Jan 2020 12:13:12 +0100 (CET) Received: from smtp1.de.adit-jv.com ([127.0.0.1]) by localhost (smtp1.de.adit-jv.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id bzHX_jsfoomi; Thu, 9 Jan 2020 12:13:06 +0100 (CET) Received: from HI2EXCH01.adit-jv.com (hi2exch01.adit-jv.com [10.72.92.24]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-SHA384 (256/256 bits)) (No client certificate requested) by smtp1.de.adit-jv.com (Postfix) with ESMTPS id CA6A13C00B7; Thu, 9 Jan 2020 12:13:06 +0100 (CET) Received: from lxhi-065.adit-jv.com (10.72.93.66) by HI2EXCH01.adit-jv.com (10.72.92.24) with Microsoft SMTP Server (TLS) id 14.3.468.0; Thu, 9 Jan 2020 12:13:06 +0100 Date: Thu, 9 Jan 2020 12:13:06 +0100 From: Eugeniu Rosca To: SZEDER =?utf-8?B?R8OhYm9y?= CC: Eugeniu Rosca , Elijah Newren , , , , , Eugeniu Rosca Subject: Re: Unreliable 'git rebase --onto' Message-ID: <20200109111306.GB1349@lxhi-065.adit-jv.com> References: <20200108214349.GA17624@lxhi-065.adit-jv.com> <20200108223557.GE32750@szeder.dev> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200108223557.GE32750@szeder.dev> X-Originating-IP: [10.72.93.66] Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org Hi Szeder, On Wed, Jan 08, 2020 at 11:35:57PM +0100, SZEDER Gábor wrote: > This is a known issue with the 'am' backend of 'git rebase'. > > The good news is that work is already well under way to change the > default backend from 'am' to 'merge', which will solve this issue. > From the log message of aa523de170 (rebase: change the default backend > from "am" to "merge", 2019-12-24): > > The am-backend drops information and thus limits what we can do: > [...] > * reduction in context from only having a few lines beyond those > changed means that when context lines are non-unique we can apply > patches incorrectly.[2] > [...] > [2] https://lore.kernel.org/git/CABPp-BGiu2nVMQY_t-rnFR5GQUz_ipyEE8oDocKeO+> > > Alas, there is unexpected bad news: with that commit the runtime of > your 'git rebase --onto' command goes from <1sec to over 50secs. > Cc-ing Elijah, author of that patch... [$.02] I would personally take the route of regaining users' trust in 'git rebase' first, with fixing the performance penalty later on. I was quite impressed by the recent 2.24.0 performance improvements, which tells there might be room for improvement for `git rebase` too, once it is fixed. -- Best Regards, Eugeniu