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From: Linus Torvalds <torvalds@osdl.org>
To: Davide Libenzi <davidel@xmailserver.org>
Cc: Nicolas Pitre <nico@cam.org>, Sergey Vlasov <vsu@altlinux.ru>,
	Junio C Hamano <junkio@cox.net>,
	git@vger.kernel.org
Subject: Re: heads-up: git-index-pack in "next" is broken
Date: Wed, 18 Oct 2006 14:48:43 -0700 (PDT)	[thread overview]
Message-ID: <Pine.LNX.4.64.0610181434510.3962@g5.osdl.org> (raw)
In-Reply-To: <Pine.LNX.4.64.0610181407040.18885@alien.or.mcafeemobile.com>



On Wed, 18 Oct 2006, Davide Libenzi wrote:
> 
> The hash value (hence the hash bucket index) simply directs you to the 
> bucket where a real record-compare loop is performed.

As far as I can tell not all loops do a real "record-compare" thing.

Some of the hash loops _only_ look at the hash, and as such a bad hash 
will do more than just cause bad performance, it will actually degrade the 
diff itself. Isn't that what XDL_MAX_EQLIMIT effectively does?

Btw, the binary delta generator doesn't seem to have this issue at all: it 
uses "unsigned int" for the hash values, so the xdiff delta generation 
will give the same exact results on 32-bit and 64-bit architectures.

Or was that one of the changes by Nico? (I only looked at the git version 
of that code)

		Linus

  reply	other threads:[~2006-10-18 21:49 UTC|newest]

Thread overview: 33+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-10-17  4:55 heads-up: git-index-pack in "next" is broken Junio C Hamano
2006-10-17 15:39 ` Nicolas Pitre
2006-10-17 16:07   ` Junio C Hamano
2006-10-17 17:00     ` Nicolas Pitre
2006-10-17 18:11       ` Junio C Hamano
2006-10-17 18:47         ` Nicolas Pitre
2006-10-17 19:36           ` Sergey Vlasov
2006-10-17 20:10             ` Junio C Hamano
2006-10-17 20:25               ` Nicolas Pitre
2006-10-17 20:23             ` Nicolas Pitre
2006-10-17 20:51               ` Linus Torvalds
2006-10-17 21:21                 ` Nicolas Pitre
2006-10-17 21:46                   ` Linus Torvalds
2006-10-18  0:20                     ` Nicolas Pitre
2006-10-18  0:57                       ` Linus Torvalds
2006-10-18  2:08                         ` Nicolas Pitre
2006-10-18  3:12                           ` Linus Torvalds
2006-10-18  6:09                             ` Davide Libenzi
2006-10-18 14:56                               ` Linus Torvalds
2006-10-18 16:17                                 ` Davide Libenzi
2006-10-18 16:52                                   ` Linus Torvalds
2006-10-18 21:21                                     ` Davide Libenzi
2006-10-18 21:48                                       ` Linus Torvalds [this message]
2006-10-18 22:34                                         ` Davide Libenzi
2006-10-18  1:30                       ` Junio C Hamano
2006-10-18  2:23                         ` Nicolas Pitre
2006-10-18  4:16                           ` Junio C Hamano
2006-10-18  5:07                             ` Junio C Hamano
2006-10-18 10:00                               ` Johannes Schindelin
2006-10-18 13:13                                 ` Nicolas Pitre
2006-10-18 13:02                               ` Nicolas Pitre
2006-10-17 21:54                 ` Junio C Hamano
2006-10-18  1:38                   ` Nicolas Pitre

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