From: Jeff King <peff@peff.net>
To: Nguyen Thai Ngoc Duy <pclouds@gmail.com>
Cc: Michael Haggerty <mhagger@alum.mit.edu>,
git discussion list <git@vger.kernel.org>,
Junio C Hamano <gitster@pobox.com>
Subject: Re: remove_duplicates() in builtin/fetch-pack.c is O(N^2)
Date: Tue, 22 May 2012 13:01:01 -0400 [thread overview]
Message-ID: <20120522170101.GA11600@sigill.intra.peff.net> (raw)
In-Reply-To: <CACsJy8Dw+mbP+ttTP6gAfX9o4q4NyZgPYpbhS=tket=5fvBXwg@mail.gmail.com>
On Tue, May 22, 2012 at 07:18:00PM +0700, Nguyen Thai Ngoc Duy wrote:
> On Tue, May 22, 2012 at 12:45 AM, Jeff King <peff@peff.net> wrote:
> > The rails/rails network repository at GitHub (i.e., a master repo with
> > all of the objects and refs for all of the forks) has about 400K refs,
> > and has been the usual impetus for me finding and fixing these sorts of
> > quadratic problems.
>
> Off topic and pure speculation. With 400k refs, each one 20 byte in
> length, the pathname part only can take 7MB. Perhaps packed-refs
> should learn prefix compressing too, like index v4, to reduce size
> (and hopefully improve startup speed). Compressing refs/heads/ and
> refs/tags/ only could gain quite a bit already.
In this case, the packed-refs file is 30MB. Even just gzipping it takes
it down to 2MB. As far as I know, we don't ever do random access on the
file, but instead just stream it into memory.
-Peff
next prev parent reply other threads:[~2012-05-22 17:01 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-21 8:13 remove_duplicates() in builtin/fetch-pack.c is O(N^2) Michael Haggerty
2012-05-21 9:09 ` Junio C Hamano
2012-05-21 9:42 ` demerphq
2012-05-21 17:45 ` Jeff King
2012-05-21 22:14 ` Jeff King
2012-05-21 22:17 ` [PATCH 1/5] fetch-pack: sort incoming heads Jeff King
2012-05-22 20:08 ` Junio C Hamano
2012-05-22 20:23 ` Jeff King
2012-05-24 6:04 ` Jeff King
2012-05-21 22:17 ` [PATCH 2/5] fetch-pack: avoid quadratic behavior in remove_duplicates Jeff King
2012-05-21 22:19 ` [PATCH 3/5] add sorting infrastructure for list refs Jeff King
2012-05-21 22:19 ` [PATCH 4/5] fetch-pack: sort the list of incoming refs Jeff King
2012-05-21 22:23 ` [PATCH 5/5] fetch-pack: avoid quadratic loop in filter_refs Jeff King
2012-05-22 20:16 ` Junio C Hamano
2012-05-21 23:52 ` remove_duplicates() in builtin/fetch-pack.c is O(N^2) Jeff King
2012-05-22 0:07 ` Jeff King
2012-05-22 3:59 ` Michael Haggerty
2012-05-22 4:11 ` Jeff King
2012-05-22 7:15 ` Michael Haggerty
2012-05-22 7:37 ` Jeff King
2012-05-22 13:28 ` Michael Haggerty
2012-05-22 17:33 ` Jeff King
2012-05-24 12:05 ` Michael Haggerty
2012-05-25 0:17 ` Martin Fick
2012-05-25 0:39 ` Jeff King
2012-05-25 0:54 ` Martin Fick
2012-05-25 1:04 ` Jeff King
2012-05-25 1:32 ` Martin Fick
2012-05-25 6:50 ` Jeff King
2012-05-22 12:18 ` Nguyen Thai Ngoc Duy
2012-05-22 13:35 ` Michael Haggerty
2012-05-22 17:01 ` Jeff King [this message]
2012-05-22 17:35 ` Junio C Hamano
2012-05-22 17:46 ` Jeff King
2012-05-24 4:54 ` Michael Haggerty
2012-05-23 1:20 ` Nguyen Thai Ngoc Duy
2012-05-22 16:16 ` Junio C Hamano
2012-05-21 18:15 ` Martin Fick
2012-05-21 19:41 ` Jeff King
2012-05-21 22:08 ` Junio C Hamano
2012-05-21 22:24 ` Jeff King
2012-05-22 5:51 ` Martin Fick
2012-05-22 18:21 ` Jeff King
2012-05-22 22:19 ` Martin Fick
2012-05-22 23:23 ` Junio C Hamano
2012-05-23 0:46 ` Martin Fick
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120522170101.GA11600@sigill.intra.peff.net \
--to=peff@peff.net \
--cc=git@vger.kernel.org \
--cc=gitster@pobox.com \
--cc=mhagger@alum.mit.edu \
--cc=pclouds@gmail.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).