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From: Nicolas Pitre <nico@cam.org>
To: Junio C Hamano <gitster@pobox.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Johannes Schindelin <Johannes.Schindelin@gmx.de>,
	Nix <nix@esperi.org.uk>, Steven Grimm <koreth@midwinter.com>,
	Git Mailing List <git@vger.kernel.org>
Subject: Re: Subject: [PATCH] git-merge-pack
Date: Thu, 06 Sep 2007 22:32:01 -0400 (EDT)	[thread overview]
Message-ID: <alpine.LFD.0.9999.0709062220450.21186@xanadu.home> (raw)
In-Reply-To: <7v7in38ce6.fsf@gitster.siamese.dyndns.org>

On Thu, 6 Sep 2007, Junio C Hamano wrote:

> Nicolas Pitre <nico@cam.org> writes:
> 
> > I wonder if this is the best way to go.  In the context of a really fast 
> > repack happening automatically after (or during) user interactive 
> > operations, the above seems a bit heavyweight and slow to me.
> 
> Honestly, I do not believe in that mode of operation that much.
> 
> "While the user is waiting for the EDITOR"?
> 
> Because you do not know how much time you will be given before
> you start, unless
> 
>  (1) your process can be snapshotted and you can restart at the
>      next chance; or
> 
>  (2) it is so cheap and you can afford to abort and start over
>      from scratch at the next chance; or
> 
>  (3) it is so quick that you can simply have the user wait until
>      you are done without adding too much latency to be annoying,
>      when you cannnot finish before the EDITOR come back;

I think we have to aim for #3.  "Automatic" certainly doesn't imply "can 
be slow".  It should be reasonably instantaneous, otherwise it'll become 
annoying quickly enough.  If it can't be (almost) instantaneous in 99% 
of normal cases, then I think it simply should be remain asynchronously 
througha manual invokation of 'git gc' and we only need to teach/remind 
people about it more strongly.

> >> An obvious next steps that can be done in parallel by interested
> >> parties would be:
> >> 
> >>  (1) come up with a way to give "name" aka "clustering cue" (I
> >>      think this is very hard);
> >
> > It is, and IMHO not worth it.  If you do it separately from the usual 
> > pack-objects process you'll perform extra IO and decompression when 
> > walking tree objects just to reconstruct those paths, becoming really 
> > slow by the context definition I provided above.
> 
> Well, I said "name" in quotes because you do _NOT_ have to give
> the real name.  I was not thinking about doing the actual tree
> traversal at all.  What you need to do is to come up with a
> token that is the same for the objects in the same deltification
> chain so that they cluster together, and that should be doable
> by looking at the delta chain patterns inside a packfile.

Obviously!  Sorry for being slow.

But I still think that a single repack pass should already be able to 
pick loose objects and selected (small) packs, and produce a pack with 
them all.  No need for a separate merge-pack I'd say.


Nicolas

  reply	other threads:[~2007-09-07  2:32 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
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 [this message]
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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