From: Linus Torvalds <torvalds@linux-foundation.org>
To: Junio C Hamano <gitster@pobox.com>
Cc: Johannes Schindelin <Johannes.Schindelin@gmx.de>,
Nicolas Pitre <nico@cam.org>, Nix <nix@esperi.org.uk>,
Steven Grimm <koreth@midwinter.com>,
Git Mailing List <git@vger.kernel.org>
Subject: Re: People unaware of the importance of "git gc"?
Date: Thu, 6 Sep 2007 19:15:58 +0100 (BST) [thread overview]
Message-ID: <alpine.LFD.0.999.0709061906010.5626@evo.linux-foundation.org> (raw)
In-Reply-To: <7vk5r3adlx.fsf@gitster.siamese.dyndns.org>
On Thu, 6 Sep 2007, Junio C Hamano wrote:
>
> I thought the whole point of "gc --auto" was to have something
> that does not lose/prune any objects, even the ones that do not
> seem to be referenced from anywhere. That is why invocations of
> "git gc --auto" do not say --prune as you saw the second patch,
> and the repack command "gc --auto" runs is "repack -d -l"
> instead of "repack -a -d -l", which means that it does run
> git-prune-packed after repacking but not git-prune.
I think "repack -d -l" should be ok from a safety perspective, but I'd
also like to say that always running it incrementally is going to largely
suck after a time.
IOW, if you get lots of small incrmental packs, after a while you really
*do* need to do "git gc" to get the real pack generated.
In the case I saw, James really had hundreds of pack-files. That makes all
our object lookups suck. Yes, not having loose objects at all is a big
deal too, and yes, we try to start from the last pack-file we found (for
the locality that we hope is there), but it's still pretty bad from a
cache usage standpoint, and when we create a new object, we'll first
search (in vain) in all the hundreds of pack-files.
So would "git gc --auto" have helped James? I'm sure it would have. But he
already had lots of pack-files from doing "git fetch/pull", and while
doing the "git gc --auto" will likely *delay* the point where you need to
do a full repack, it doesn't make it go away.
We still need to tell people to do a full git gc at some point, or do it
for them. And the longer you delay doing it, the more expensive it's going
to get to do and/or the worse the final packing is going to be (especially
if it ends up reusing non-optimal packing decisions from the smaller
packs).
So I think the --auto stuff is still worth it, but it's really just
pushing the pain somewhat further out.
(In the kernel community, if you fetch my tree daily, you really *are*
going to have hundreds and hundreds of packfiles just from doing that).
So I'd really like us to also remind people to do a *real* and full "git
gc", not just the incremental ones.
Linus
next prev parent reply other threads:[~2007-09-06 18:17 UTC|newest]
Thread overview: 97+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-09-05 7:09 People unaware of the importance of "git gc"? Linus Torvalds
2007-09-05 7:21 ` Martin Langhoff
2007-09-05 7:37 ` Karl Hasselström
2007-09-05 7:30 ` Junio C Hamano
2007-09-05 7:26 ` Tomash Brechko
2007-09-05 8:13 ` Johan Herland
2007-09-05 8:39 ` Matthieu Moy
2007-09-05 8:41 ` Johan Herland
2007-09-05 8:47 ` David Kastrup
2007-09-05 8:51 ` Pierre Habouzit
2007-09-05 9:02 ` David Kastrup
2007-09-05 9:04 ` Matthieu Moy
2007-09-05 8:51 ` Wincent Colaiuta
2007-09-05 7:42 ` Pierre Habouzit
2007-09-05 8:16 ` Junio C Hamano
2007-09-05 8:50 ` Steven Grimm
[not found] ` <86ps0xcwxo.fsf@lola.quinscape.zz>
2007-09-05 9:07 ` Steven Grimm
2007-09-05 9:13 ` David Kastrup
2007-09-05 9:07 ` Junio C Hamano
2007-09-05 9:27 ` Martin Langhoff
2007-09-05 9:33 ` Matthieu Moy
2007-09-05 14:17 ` Johan De Messemaeker
2007-09-05 17:31 ` Matthieu Moy
2007-09-05 23:56 ` Jeff King
2007-09-05 9:13 ` David Kastrup
2007-09-05 9:14 ` Pierre Habouzit
2007-09-05 17:51 ` Nix
2007-09-05 18:14 ` Steven Grimm
2007-09-05 18:22 ` Nix
2007-09-05 18:54 ` Nicolas Pitre
2007-09-05 20:01 ` Junio C Hamano
2007-09-05 20:35 ` Nicolas Pitre
2007-09-05 21:14 ` Nix
2007-09-05 21:46 ` Junio C Hamano
2007-09-05 23:04 ` Nicolas Pitre
2007-09-05 23:42 ` Junio C Hamano
2007-09-06 0:27 ` Carlos Rica
2007-09-06 5:55 ` David Kastrup
2007-09-05 21:49 ` Junio C Hamano
2007-09-05 21:59 ` Invoke "git gc --auto" from commit, merge, am and rebase Junio C Hamano
2007-09-06 2:39 ` Shawn O. Pearce
2007-09-05 20:37 ` [PATCH] Invoke "git gc --auto" from "git add" and "git fetch" Junio C Hamano
[not found] ` <69b0c0350709051357ifa547aarfe3e0b36cf9be98f@mail.gmail.com>
2007-09-05 20:59 ` Fwd: " Govind Salinas
2007-09-06 12:02 ` Johannes Schindelin
2007-09-05 21:18 ` People unaware of the importance of "git gc"? Alex Riesen
2007-09-06 2:44 ` Russ Dill
2007-09-06 2:52 ` Shawn O. Pearce
2007-09-06 9:28 ` Andreas Ericsson
2007-09-06 2:45 ` Shawn O. Pearce
2007-09-06 2:49 ` Steven Grimm
2007-09-06 2:56 ` Shawn O. Pearce
2007-09-06 15:54 ` Johannes Schindelin
2007-09-06 17:49 ` Junio C Hamano
2007-09-06 18:15 ` Linus Torvalds [this message]
2007-09-06 18:29 ` Steven Grimm
2007-09-06 23:12 ` Subject: [PATCH] git-merge-pack Junio C Hamano
2007-09-06 23:35 ` Linus Torvalds
2007-09-07 0:51 ` Nicolas Pitre
2007-09-07 1:58 ` Junio C Hamano
2007-09-07 2:32 ` Nicolas Pitre
2007-09-07 4:07 ` Shawn O. Pearce
2007-09-07 4:43 ` Junio C Hamano
2007-09-08 9:50 ` [PATCH] make sha1_file.c::matches_pack_name() available to others Junio C Hamano
2007-09-08 10:01 ` [PATCH] pack-objects --repack-unpacked Junio C Hamano
2007-09-07 7:11 ` Subject: [PATCH] git-merge-pack Johannes Sixt
2007-09-07 7:34 ` Junio C Hamano
2007-09-07 7:24 ` Andy Parkins
2007-09-07 4:48 ` People unaware of the importance of "git gc"? Shawn O. Pearce
2007-09-07 10:12 ` Johannes Schindelin
2018-10-07 18:28 ` What's so special about objects/17/ ? Ævar Arnfjörð Bjarmason
2018-10-07 18:35 ` Johannes Sixt
2018-10-07 19:06 ` Ævar Arnfjörð Bjarmason
2018-10-07 22:39 ` Johannes Sixt
2018-10-08 0:54 ` Junio C Hamano
2018-10-07 19:46 ` Junio C Hamano
2018-10-07 20:07 ` Junio C Hamano
2018-10-08 19:17 ` Stefan Beller
2018-10-09 1:03 ` Junio C Hamano
2018-10-09 17:37 ` Stefan Beller
2018-10-10 1:10 ` Junio C Hamano
2018-10-10 19:08 ` Stefan Beller
2018-10-08 10:36 ` Ævar Arnfjörð Bjarmason
2018-10-09 1:07 ` Junio C Hamano
2018-10-09 17:40 ` Stefan Beller
2007-09-05 8:16 ` People unaware of the importance of "git gc"? David Kastrup
2007-09-05 16:47 ` Govind Salinas
2007-09-05 17:19 ` Carl Worth
2007-09-05 17:55 ` Jing Xue
2007-09-05 17:35 ` Steven Grimm
2007-09-05 18:28 ` Nix
2007-09-05 17:44 ` J. Bruce Fields
2007-09-05 18:46 ` Brandon Casey
2007-09-05 19:09 ` David Kastrup
2007-09-05 19:13 ` J. Bruce Fields
2007-09-05 19:43 ` David Kastrup
2007-09-05 19:20 ` Mike Hommey
2007-09-05 21:07 ` Alex Riesen
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