From: Jakub Narebski <jnareb@gmail.com>
To: "Shawn O. Pearce" <spearce@spearce.org>
Cc: Avery Pennarun <apenwarr@gmail.com>,
Joshua Juran <jjuran@gmail.com>,
Finn Arne Gangstad <finnag@pvv.org>,
git@vger.kernel.org
Subject: Re: inotify daemon speedup for git [POC/HACK]
Date: Wed, 28 Jul 2010 06:06:22 -0700 (PDT) [thread overview]
Message-ID: <m3tynjkb90.fsf@localhost.localdomain> (raw)
In-Reply-To: <20100728000009.GE25268@spearce.org>
"Shawn O. Pearce" <spearce@spearce.org> writes:
> Avery Pennarun <apenwarr@gmail.com> wrote:
> >
> > While we're here, it's probably worth mentioning that git's index file
> > format (which stores a sequential list of full paths in alphabetical
> > order, instead of an actual hierarchy) does become a bottleneck when
> > you actually have a huge number of files in your repo (like literally
> > a million). You can't actually binary search through the index! The
> > current implementation of submodules allows you to dodge that
> > scalability problem since you end up with multiple smaller index
> > files. Anyway, that's fixable too.
>
> Yes.
>
> More than once I've been tempted to rewrite the on-disk (and I guess
> in-memory) format of the index. And then I remember how painful that
> stuff is in either C git.git or JGit, and I back away slowly. :-)
>
> Ideally the index is organized the same way the trees are, but
> you still can't do a really good binary search because of the
> ass-backwards name sorting rule for trees. But for performance
> reasons you still want to keep the entire index in a single file,
> an index per directory (aka SVN/CVS) is too slow for the common
> case of <30k files.
I guess that modern filesystems solve the problem of very many files
in a single directory somehow (hash tables?). Perhaps the index file
could borrow some such mechanism as an extension.
Index for index?
--
Jakub Narebski
Poland
ShadeHawk on #git
next prev parent reply other threads:[~2010-07-28 13:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-27 12:20 inotify daemon speedup for git [POC/HACK] Finn Arne Gangstad
2010-07-27 23:29 ` Avery Pennarun
2010-07-27 23:39 ` Joshua Juran
2010-07-27 23:51 ` Avery Pennarun
2010-07-28 0:00 ` Shawn O. Pearce
2010-07-28 0:18 ` Avery Pennarun
2010-07-28 1:14 ` Joshua Juran
2010-07-28 1:31 ` Avery Pennarun
2010-07-28 6:03 ` Sverre Rabbelier
2010-07-28 6:06 ` Jonathan Nieder
2010-07-28 7:44 ` Ævar Arnfjörð Bjarmason
2010-07-28 11:08 ` Theodore Tso
2010-07-28 8:20 ` Nguyen Thai Ngoc Duy
2010-08-13 17:53 ` Enrico Weigelt
2010-07-28 13:09 ` Jakub Narebski
2010-07-28 13:06 ` Jakub Narebski [this message]
2010-08-13 17:58 ` Enrico Weigelt
2010-07-27 23:58 ` Sverre Rabbelier
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