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From: Theodore Ts'o <tytso@mit.edu>
To: Junio C Hamano <gitster@pobox.com>
Cc: "Christoph Hellwig" <hch@lst.de>,
	"Linus Torvalds" <torvalds@linux-foundation.org>,
	"Ævar Arnfjörð Bjarmason" <avarab@gmail.com>,
	"Git Mailing List" <git@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>,
	"Chris Mason" <clm@fb.com>
Subject: Re: [PATCH] enable core.fsyncObjectFiles by default
Date: Sat, 20 Jan 2018 17:14:45 -0500
Message-ID: <20180120221445.GA4451@thunk.org> (raw)
In-Reply-To: <xmqqzi59psxt.fsf@gitster.mtv.corp.google.com>

On Fri, Jan 19, 2018 at 11:08:46AM -0800, Junio C Hamano wrote:
> So..., is it fair to say that the one you sent in
> 
>   https://public-inbox.org/git/20180117193510.GA30657@lst.de/
> 
> is the best variant we have seen in this thread so far?  I'll keep
> that in my inbox so that I do not forget, but I think we would want
> to deal with a hotfix for 2.16 on case insensitive platforms before
> this topic.

It's a simplistic fix, but it will work.  There may very well be
certain workloads which generate a large number of loose objects
(e.g., git repack -A) which will make things go significantly more
slowly as a result.  It might very well be the case that if nothing
else is going on, something like "write all the files without
fsync(2), then use syncfs(2)" would be much faster.  The downside with
that approach is if indeed you were downloading a multi-gigabyte DVD
image at the same time, the syncfs(2) will force a writeback of the
partially writte DVD image, or some other unrelated files.

But if the goal is to just change the default, and then see what
shakes out, and then apply other optimizations later, that's certainly
a valid result.  I've never been fond of the "git repack -A" behavior
where it can generate huge numbers of loose files.  I'd much prefer it
if the other objects ended up in a separate pack file, and then some
other provision made for nuking that pack file some time later.  But
that's expanding the scope significantly over what's currently being
discussed.

						- Ted

  reply index

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-17 18:48 Christoph Hellwig
2018-01-17 19:04 ` Junio C Hamano
2018-01-17 19:35   ` Christoph Hellwig
2018-01-17 20:05     ` Andreas Schwab
2018-01-17 19:37   ` Matthew Wilcox
2018-01-17 19:42     ` Christoph Hellwig
2018-01-17 21:44   ` Ævar Arnfjörð Bjarmason
2018-01-17 22:07     ` Linus Torvalds
2018-01-17 22:25       ` Linus Torvalds
2018-01-17 23:16       ` Ævar Arnfjörð Bjarmason
2018-01-17 23:42         ` Linus Torvalds
2018-01-17 23:52       ` Theodore Ts'o
2018-01-17 23:57         ` Linus Torvalds
2018-01-18 16:27           ` Christoph Hellwig
2018-01-19 19:08             ` Junio C Hamano
2018-01-20 22:14               ` Theodore Ts'o [this message]
2018-01-20 22:27                 ` Junio C Hamano
2018-01-22 15:09                   ` Ævar Arnfjörð Bjarmason
2018-01-22 18:09                     ` Theodore Ts'o
2018-01-23  0:47                       ` Jeff King
2018-01-23  5:45                         ` Theodore Ts'o
2018-01-23 16:17                           ` Jeff King
2018-01-23  0:25                     ` Jeff King
2018-01-21 21:32             ` Chris Mason
2020-09-17 11:06         ` Ævar Arnfjörð Bjarmason
2020-09-17 11:28           ` [RFC PATCH 0/2] should core.fsyncObjectFiles fsync the dir entry + docs Ævar Arnfjörð Bjarmason
2020-09-17 11:28           ` [RFC PATCH 1/2] sha1-file: fsync() loose dir entry when core.fsyncObjectFiles Ævar Arnfjörð Bjarmason
2020-09-17 13:16             ` Jeff King
2020-09-17 15:09               ` Christoph Hellwig
2020-09-17 14:09             ` Christoph Hellwig
2020-09-17 14:55               ` Jeff King
2020-09-17 14:56                 ` Christoph Hellwig
2020-09-17 15:37                   ` Junio C Hamano
2020-09-17 17:12                     ` Jeff King
2020-09-17 20:37                       ` Taylor Blau
2020-09-22 10:42               ` Ævar Arnfjörð Bjarmason
2020-09-17 20:21             ` Johannes Sixt
2020-09-22  8:24               ` Ævar Arnfjörð Bjarmason
2020-11-19 11:38                 ` Johannes Schindelin
2020-09-17 11:28           ` [RFC PATCH 2/2] core.fsyncObjectFiles: make the docs less flippant Ævar Arnfjörð Bjarmason
2020-09-17 14:12             ` Christoph Hellwig
2020-09-17 15:43             ` Junio C Hamano
2020-09-17 20:15               ` Johannes Sixt
2020-10-08  8:13               ` Johannes Schindelin
2020-10-08 15:57                 ` Ævar Arnfjörð Bjarmason
2020-10-08 18:53                   ` Junio C Hamano
2020-10-09 10:44                   ` Johannes Schindelin
2020-09-17 19:21             ` Marc Branchaud
2020-09-17 14:14           ` [PATCH] enable core.fsyncObjectFiles by default Christoph Hellwig
2020-09-17 15:30           ` Junio C Hamano
2018-01-17 20:55 ` Jeff King
2018-01-17 21:10   ` Christoph Hellwig
  -- strict thread matches above, loose matches on Subject: below --
2015-06-23 21:57 [PATCH] Enable " Stefan Beller
2015-06-23 22:21 ` Junio C Hamano
2015-06-23 23:29   ` Theodore Ts'o
2015-06-24  5:32     ` Junio C Hamano
2015-06-24 14:30       ` Theodore Ts'o
2015-06-24  1:07 ` Duy Nguyen
2015-06-24  3:37 ` Jeff King
2015-06-24  5:20   ` Junio C Hamano

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