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From: Will Palmer <wmpalmer@gmail.com>
To: Jeff King <peff@peff.net>
Cc: tytso@mit.edu, Avery Pennarun <apenwarr@gmail.com>, git@vger.kernel.org
Subject: Re: Why is "git tag --contains" so slow?
Date: Tue, 06 Jul 2010 16:31:43 +0100	[thread overview]
Message-ID: <1278430303.32094.15.camel@wpalmer.simply-domain> (raw)
In-Reply-To: <20100706115826.GA15413@sigill.intra.peff.net>

On Tue, 2010-07-06 at 07:58 -0400, Jeff King wrote:
> On Mon, Jul 05, 2010 at 10:10:12AM -0400, tytso@mit.edu wrote:
> > I'm not sure this is a good tradeoff, but given in practice how rarely
> > most developers go back in time more than say, 12-24 months, maybe
> > it's worth doing.  What do you think?
> 
> I'm not sure. I am tempted to just default it to 86400 and go no
> further.  People who care about archaeology can turn off traversal
> cutoffs if they like, and as the skewed history ages, people get less
> likely to look at it. We could also pick half a year or some high number
> as the default allowable. The performance increase is still quite
> noticeable there, and it covers the only large skew we know about. I'd
> be curious to see if other projects have skew, and how much.
> 
> -Peff

Is it wrong to expect that git perform poorly in the edge-cases (hugely
skewed timestamps), but that it perform /correctly/ in all cases?

Clearly, marking already-traversed histories was the right thing to do,
and if I read correctly, made a good improvement on its own. But you
seem to have crossed a line at some point between "optimization" and
"potentially giving the wrong answer because it's faster"

Or am I just misunderstanding here?

  reply	other threads:[~2010-07-06 15:31 UTC|newest]

Thread overview: 46+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-01  0:54 Why is "git tag --contains" so slow? Theodore Ts'o
2010-07-01  0:58 ` Shawn O. Pearce
2010-07-03 23:27   ` Sam Vilain
2010-07-01  1:00 ` Avery Pennarun
2010-07-01 12:17   ` tytso
2010-07-01 15:03     ` Jeff King
2010-07-01 15:38       ` Jeff King
2010-07-02 19:26         ` tytso
2010-07-03  8:06           ` Jeff King
2010-07-04  0:55             ` tytso
2010-07-05 12:27               ` Jeff King
2010-07-05 12:33                 ` [RFC/PATCH 1/4] tag: speed up --contains calculation Jeff King
2010-10-13 22:07                   ` Jonathan Nieder
2010-10-13 22:56                   ` Clemens Buchacher
2011-02-23 15:51                   ` Ævar Arnfjörð Bjarmason
2011-02-23 16:39                     ` Jeff King
2010-07-05 12:34                 ` [RFC/PATCH 2/4] limit "contains" traversals based on commit timestamp Jeff King
2010-10-13 23:21                   ` Jonathan Nieder
2010-07-05 12:35                 ` [RFC/PATCH 3/4] default core.clockskew variable to one day Jeff King
2010-07-05 12:36                 ` [RFC/PATCH 4/4] name-rev: respect core.clockskew Jeff King
2010-07-05 12:39                 ` Why is "git tag --contains" so slow? Jeff King
2010-10-14 18:59                   ` Jonathan Nieder
2010-10-16 14:32                     ` Clemens Buchacher
2010-10-27 17:11                       ` Jeff King
2010-10-28  8:07                         ` Clemens Buchacher
2010-07-05 14:10                 ` tytso
2010-07-06 11:58                   ` Jeff King
2010-07-06 15:31                     ` Will Palmer [this message]
2010-07-06 16:53                       ` tytso
2010-07-08 11:28                         ` Jeff King
2010-07-08 13:21                           ` Will Palmer
2010-07-08 13:54                             ` tytso
2010-07-07 17:45                       ` Jeff King
2010-07-08 10:29                         ` Theodore Tso
2010-07-08 11:12                           ` Jakub Narebski
2010-07-08 19:29                             ` Nicolas Pitre
2010-07-08 19:39                               ` Avery Pennarun
2010-07-08 20:13                                 ` Nicolas Pitre
2010-07-08 21:20                                   ` Jakub Narebski
2010-07-08 21:30                                     ` Sverre Rabbelier
2010-07-08 23:10                                       ` Nicolas Pitre
2010-07-08 23:15                                     ` Nicolas Pitre
2010-07-08 11:31                           ` Jeff King
2010-07-08 14:35                           ` Johan Herland
2010-07-08 19:06                           ` Nicolas Pitre
2010-07-07 17:50                       ` Jeff King

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