From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-2.6 required=3.0 tests=AWL,BAYES_00, FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS, RCVD_IN_DNSWL_HI,T_RP_MATCHES_RCVD shortcircuit=no autolearn=no autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 39A4F1F404 for ; Thu, 4 Jan 2018 17:35:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752062AbeADRfn (ORCPT ); Thu, 4 Jan 2018 12:35:43 -0500 Received: from mout.gmx.net ([212.227.15.18]:55320 "EHLO mout.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752036AbeADRfl (ORCPT ); Thu, 4 Jan 2018 12:35:41 -0500 Received: from [192.168.0.129] ([37.201.193.20]) by mail.gmx.com (mrgmx002 [212.227.17.190]) with ESMTPSA (Nemesis) id 0MY7dI-1eSfII1pi4-00UofB; Thu, 04 Jan 2018 18:35:30 +0100 Date: Thu, 4 Jan 2018 18:35:30 +0100 (STD) From: Johannes Schindelin X-X-Sender: virtualbox@MININT-6BKU6QN.europe.corp.microsoft.com To: =?UTF-8?Q?=C3=86var_Arnfj=C3=B6r=C3=B0_Bjarmason?= cc: Jonathan Nieder , git@vger.kernel.org, Junio C Hamano , Jeff King , Jeff Hostetler , Johannes Sixt , git-for-windows@googlegroups.com Subject: Re: [PATCH 2/2] Windows: stop supplying BLK_SHA1=YesPlease by default In-Reply-To: <87k1x7q800.fsf@evledraar.gmail.com> Message-ID: References: <20171227230038.14386-1-avarab@gmail.com> <20171227230038.14386-3-avarab@gmail.com> <20171227234237.GC181628@aiede.mtv.corp.google.com> <87k1x7q800.fsf@evledraar.gmail.com> User-Agent: Alpine 2.21.1 (DEB 209 2017-03-23) MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="8323329-1482691442-1515087331=:31" X-Provags-ID: V03:K0:Hvu62ZyqwLq26tULkKuYpX4GiE00YX8z3e9FlhPI0gqHDz1sxvn zMO4PJsJ02v60G/UJQS4+AExYmwSfYDZLDXiOm6zjjoa47e7da2bv9wMHZ8VUIxi+1f0SZ2 RkTb1jvnvjFI6B1QSWwq5WzJZdzjzNYef0wl1zMkFjIFq+qoZnfh+mdMOZ0Hvh76JtBMQ7Z xEaY5ovxWXOOP1Vej4tIA== X-UI-Out-Filterresults: notjunk:1;V01:K0:W7wZR/Q2iRs=:pL7OuQvlPTg9Tbs7xgnZY2 V9C8QyWtmLo8RaaftF3ThVVv66r8HdGsz1cEnQZ9UawwwWKD6f4JZhKpU9dprf/OQFR4gaBQa Ns3C020TyMA3zORUKHkccFBud6GJFHnta3MNK+QmiC4TsLrE7begwciqeIhJhFjORLlk0Cm0p BF3zA1SVSV4q7m52xN10uAcyE0O8voRZ4aAgq+AFJy2DKfCTIg5EfMj3Ze9uf1B+mOV8JWT9r /2upUQ89ckJIAy4GKi3BlgbszwjDQjCSVyaOpfPwB3jCp7JLmf9aczeTOz8+qe5Xe2FcbFXdj sMZk+28zXeBxs4WcTjt5I53/kAH6TSBFr1inwpiLks1LJlCCRy+krxAVNb8P+6Z5ImrPy/7fu gHlBdr8khnsnQFwq41bG/JGGW6tzPyAs2EOOxMjdUg20dTDM90DNj8HfWVYNYaeEN2zrhQvaM 31ieq8Bcbh+YwyhKfBw23q+mTTM+cbjW8v+lrjezlCAqDtE6df2GW/mFYyWbwUbNr6lSph8WH 5Zu2gri0SqOQpjg/82InmQ2WdOUYBvDAivhGR4BHzDP072RNSPrwgCC9GmdRpZPD3RkxLvFDV e2uRZyFU4YN/tVhD3K49/TjuWzFLwNnn5FxSVLHF/HRMkHaiAC3VnYKc/oa32vB3acLmVrhdb l+/ST+N4ZMr2hWBBSy2B8vEZdoKJG/aeKgLbliGsLDEUIHc+jXs9jYoRWiJRfncVQa2VxuDMr fGa/eh+6XUypyLhelKGjKz+FVD3Z65+AiZBGDF7FGQcZ3DB7exQYbfSol2zW4eGOVNzZuLkfi Q1EJ/NJURoxljsQcNMaJ9HEP891HpxXAwUtOpU/z12joqHRdKnNU/veGZTEd3xz47QirynH Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323329-1482691442-1515087331=:31 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Hi, On Thu, 28 Dec 2017, =C3=86var Arnfj=C3=B6r=C3=B0 Bjarmason wrote: > On Wed, Dec 27 2017, Jonathan Nieder jotted: >=20 > > +git-for-windows > > =C3=86var Arnfj=C3=B6r=C3=B0 Bjarmason wrote: > > > >> Using BLK_SHA1 in lieu of the OpenSSL routines was done in [1], but > >> since DC_SHA1 is now the default for git in general it makes sense for > >> Windows to use that too, this looks like something that was missed > >> back in [2]. > >> > >> As noted in [3] OpenSSL has a performance benefit compared to BLK_SHA1 > >> on MinGW, so perhaps that and the Windows default should be changed > >> around again, but that's a topic for another series, it seems clear > >> that this specific flag is nobody's explicit intention. > > > > I have some memory of performance issues on Windows when DC_SHA1 was > > introduced leading to interest in a mixed configuration with DC_SHA1 > > only being used where it is security sensitive (e.g. for object naming > > but not for packfile trailers). > > > > Did anything come of that? >=20 > This was Johannes Schindelin (CC'd) on-list when the sha1dc discussion > first came up earlier this year. I.e. it's slower, so we could use > openssl on trusted data and sha1dc on untrusted data, but nothing came > of that. The performance degradation is noticeable, as far as I can see. And no, we have not yet worked on the hyprid SHA-1-DC solution, as we expect bigger benefits from trying to avoid unnecessary SHA-1 calculation to begin with (read: we will try to catch bigger fish first). All of this may also become moot if we ever get off the ground with SHA-256 (or whatever we will use then). Ciao, Dscho --8323329-1482691442-1515087331=:31--