From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: "Ævar Arnfjörð Bjarmason" <firstname.lastname@example.org>
Cc: Jonathan Nieder <email@example.com>,
firstname.lastname@example.org, Junio C Hamano <email@example.com>,
Jeff King <firstname.lastname@example.org>,
Jeff Hostetler <email@example.com>,
Johannes Sixt <firstname.lastname@example.org>,
Subject: Re: [PATCH 2/2] Windows: stop supplying BLK_SHA1=YesPlease by default
Date: Thu, 4 Jan 2018 18:35:30 +0100 (STD) [thread overview]
Message-ID: <alpine.DEB.22.214.171.1241041833410.31@MININT-6BKU6QN.europe.corp.microsoft.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 1658 bytes --]
On Thu, 28 Dec 2017, Ævar Arnfjörð Bjarmason wrote:
> On Wed, Dec 27 2017, Jonathan Nieder jotted:
> > +git-for-windows
> > Ævar Arnfjörð Bjarmason wrote:
> >> Using BLK_SHA1 in lieu of the OpenSSL routines was done in , 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 .
> >> As noted in  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?
> 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).
prev parent reply other threads:[~2018-01-04 17:35 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-27 23:00 [PATCH 0/2] When DC_SHA1 was made the default we missed a spot Ævar Arnfjörð Bjarmason
2017-12-27 23:00 ` [PATCH 1/2] Makefile: NO_OPENSSL=1 should no longer imply BLK_SHA1=1 Ævar Arnfjörð Bjarmason
2017-12-27 23:39 ` Jonathan Nieder
2017-12-28 14:07 ` [PATCH v2 0/2] When DC_SHA1 was made the default we missed a spot Ævar Arnfjörð Bjarmason
2017-12-28 14:07 ` [PATCH v2 1/2] Makefile: NO_OPENSSL=1 should no longer imply BLK_SHA1=1 Ævar Arnfjörð Bjarmason
2017-12-28 19:05 ` Jonathan Nieder
2017-12-28 14:07 ` [PATCH v2 2/2] Windows: stop supplying BLK_SHA1=YesPlease by default Ævar Arnfjörð Bjarmason
2017-12-28 19:04 ` Jonathan Nieder
2018-01-04 17:33 ` Johannes Schindelin
2018-01-04 18:30 ` Ævar Arnfjörð Bjarmason
2018-01-05 18:52 ` Junio C Hamano
2017-12-27 23:00 ` [PATCH " Ævar Arnfjörð Bjarmason
2017-12-27 23:42 ` Jonathan Nieder
2017-12-28 13:47 ` Ævar Arnfjörð Bjarmason
2018-01-04 17:35 ` Johannes Schindelin [this message]
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