From: Matt Mackall <mpm@selenic.com>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Linus Torvalds <torvalds@osdl.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
git@vger.kernel.org
Subject: Re: Mercurial 0.4b vs git patchbomb benchmark
Date: Fri, 29 Apr 2005 13:39:59 -0700 [thread overview]
Message-ID: <20050429203959.GC21897@waste.org> (raw)
In-Reply-To: <20050429203027.GK17379@opteron.random>
On Fri, Apr 29, 2005 at 10:30:27PM +0200, Andrea Arcangeli wrote:
> On Thu, Apr 28, 2005 at 11:01:57PM -0700, Matt Mackall wrote:
> > change nodes so you've got to potentially traverse all the commits to
> > reconstruct a file's history. That's gonna be O(top-level changes)
> > seeks. This introduces a number of problems:
> >
> > - no way to easily find previous revisions of a file
> > (being able to see when a particular change was introduced is a
> > pretty critical feature)
> > - no way to do bandwidth-efficient delta transfer
> > - no way to do efficient delta storage
> > - no way to do merges based on the file's history[1]
>
> And IMHO also no-way to implement a git-on-the-fly efficient network
> protocol if tons of clients connects at the same time, it would be
> dosable etc... At the very least such a system would require an huge
> amount of ram. So I see the only efficient way to design a network
> protocol for git not to use git, but to import the data into mercurial
> and to implement the network protocol on top of mercurial.
>
> The one downside is that git is sort of rock solid in the way it stores
> data on disk, it makes rsync usage trivial too, the git fsck is reliable
> and you can just sign the hash of the root of the tree and you sign
> everything including file contents. And of course the checkin is
> absolutely trivial and fast too.
Mercurial is ammenable to rsync provided you devote a read-only
repository to it on the client side. In other words, you rsync from
kernel.org/mercurial/linus to local/linus and then you merge from
local/linus to your own branch. Mercurial's hashing hierarchy is
similar to git's (and Monotone's), so you can sign a single hash of
the tree as well.
> With a more efficient diff-based storage like mercurial we'd be losing
> those fsck properties etc.. but those reliability properties don't worth
> the network and disk space they take IMHO, and the checkin time
> shouldn't be substantially different (still running in O(1) when
> appending at the head). And we could always store the hash of the
> changeset, to give it some basic self-checking.
I think I can implement a decent repository check similar to git, it's
just not been a priority.
--
Mathematics is the supreme nostalgia of our time.
next prev parent reply other threads:[~2005-04-29 20:43 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-26 0:41 Mercurial 0.3 vs git benchmarks Matt Mackall
2005-04-26 1:49 ` Daniel Phillips
2005-04-26 2:08 ` Linus Torvalds
2005-04-26 2:30 ` Mike Taht
2005-04-26 3:04 ` Linus Torvalds
2005-04-26 4:00 ` Linus Torvalds
2005-04-26 11:13 ` Chris Mason
2005-04-26 15:09 ` Magnus Damm
2005-04-26 15:38 ` Chris Mason
2005-04-26 16:23 ` Magnus Damm
2005-04-26 18:18 ` Chris Mason
2005-04-26 20:56 ` Andrew Morton
2005-04-26 21:07 ` Linus Torvalds
2005-04-26 22:50 ` H. Peter Anvin
2005-04-26 22:56 ` Andrew Morton
2005-04-26 23:43 ` H. Peter Anvin
2005-04-27 15:01 ` Florian Weimer
2005-04-27 15:13 ` Thomas Glanzmann
2005-04-27 18:54 ` H. Peter Anvin
2005-04-27 19:01 ` Thomas Glanzmann
2005-04-27 19:57 ` Theodore Ts'o
2005-04-27 20:06 ` Thomas Glanzmann
2005-04-27 20:35 ` H. Peter Anvin
2005-04-27 20:39 ` Thomas Glanzmann
2005-04-27 20:47 ` Florian Weimer
2005-04-27 20:55 ` Florian Weimer
2005-04-27 21:04 ` H. Peter Anvin
2005-04-27 21:06 ` Florian Weimer
2005-04-27 21:32 ` Theodore Ts'o
2005-04-27 19:55 ` Theodore Ts'o
2005-04-27 6:34 ` Ingo Molnar
2005-04-27 21:10 ` Bill Davidsen
2005-04-27 21:39 ` Linus Torvalds
2005-04-26 16:42 ` Linus Torvalds
2005-04-26 17:39 ` Chris Mason
2005-04-26 19:52 ` Chris Mason
2005-04-26 18:15 ` H. Peter Anvin
2005-04-26 20:30 ` Bill Davidsen
2005-04-26 16:11 ` Bill Davidsen
2005-04-26 4:01 ` Matt Mackall
2005-04-26 4:20 ` Linus Torvalds
2005-04-26 4:09 ` Chris Wedgwood
2005-04-26 4:22 ` Andreas Gal
2005-04-26 4:22 ` Linus Torvalds
2005-04-29 6:01 ` Mercurial 0.4b vs git patchbomb benchmark Matt Mackall
2005-04-29 6:40 ` Sean
2005-04-29 7:40 ` Matt Mackall
2005-04-29 8:40 ` Sean
2005-04-29 14:34 ` Linus Torvalds
2005-04-29 15:18 ` Morten Welinder
2005-04-29 16:52 ` Matt Mackall
2005-05-02 16:10 ` Bill Davidsen
2005-05-02 19:02 ` Sean
2005-05-02 22:02 ` Linus Torvalds
2005-05-02 22:30 ` Matt Mackall
2005-05-02 22:49 ` Linus Torvalds
2005-05-03 0:00 ` Matt Mackall
2005-05-03 2:48 ` Linus Torvalds
2005-05-03 3:29 ` Matt Mackall
2005-05-03 4:18 ` Linus Torvalds
2005-05-03 4:24 ` Linus Torvalds
2005-05-03 4:27 ` Matt Mackall
2005-05-03 8:45 ` Chris Wedgwood
2005-04-29 15:44 ` Tom Lord
2005-04-29 15:58 ` Linus Torvalds
2005-04-29 17:34 ` Tom Lord
2005-04-29 17:56 ` Linus Torvalds
2005-04-29 18:08 ` Tom Lord
2005-04-29 18:33 ` Sean
2005-04-29 18:54 ` Tom Lord
2005-04-29 19:13 ` Sean
2005-05-02 16:15 ` Bill Davidsen
2005-04-29 16:37 ` Matt Mackall
2005-04-29 17:09 ` Linus Torvalds
2005-04-29 19:12 ` Matt Mackall
2005-04-29 19:50 ` Linus Torvalds
2005-04-29 20:23 ` Matt Mackall
2005-04-29 20:49 ` Linus Torvalds
2005-04-29 21:20 ` Matt Mackall
2005-04-29 16:46 ` Bill Davidsen
2005-04-29 20:19 ` Andrea Arcangeli
2005-04-29 22:30 ` Olivier Galibert
2005-04-29 22:47 ` Andrea Arcangeli
2005-04-29 20:30 ` Andrea Arcangeli
2005-04-29 20:39 ` Matt Mackall [this message]
2005-04-30 2:52 ` Andrea Arcangeli
2005-04-30 15:20 ` Matt Mackall
2005-04-30 16:37 ` Andrea Arcangeli
2005-05-02 15:49 ` Bill Davidsen
2005-05-02 16:14 ` Valdis.Kletnieks
2005-05-03 17:40 ` Bill Davidsen
2005-05-04 2:10 ` Mercurial 0.4b vs git patchbomb benchmark (/usr/bin/env again) David A. Wheeler
2005-05-02 16:17 ` Mercurial 0.4b vs git patchbomb benchmark Andrea Arcangeli
2005-05-02 16:31 ` Linus Torvalds
2005-05-02 17:18 ` Daniel Jacobowitz
2005-05-02 17:32 ` Linus Torvalds
2005-05-02 20:54 ` Sam Ravnborg
2005-05-02 17:20 ` Ryan Anderson
2005-05-02 17:31 ` Linus Torvalds
2005-05-02 21:17 ` Kyle Moffett
2005-05-03 17:43 ` Bill Davidsen
[not found] <3YQn9-8qX-5@gated-at.bofh.it>
[not found] ` <3ZLEF-56n-1@gated-at.bofh.it>
[not found] ` <3ZM7L-5ot-13@gated-at.bofh.it>
[not found] ` <3ZN3P-69A-9@gated-at.bofh.it>
[not found] ` <3ZNdz-6gK-9@gated-at.bofh.it>
2005-05-03 1:16 ` Bodo Eggert <harvested.in.lkml@posting.7eggert.dyndns.org>
2005-05-03 1:29 ` Matt Mackall
2005-05-03 16:22 ` Bill Davidsen
2005-05-03 17:14 ` Rene Scharfe
2005-05-04 17:51 ` Bill Davidsen
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