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From: Jeff King <peff@peff.net>
To: "Nguyễn Thái Ngọc Duy" <pclouds@gmail.com>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 0/2] performance regression in mark_edges_uninteresting
Date: Mon, 20 Jan 2014 17:29:36 -0500	[thread overview]
Message-ID: <20140120222936.GA25291@sigill.intra.peff.net> (raw)
In-Reply-To: <20140120212845.GA11451@sigill.intra.peff.net>

On Mon, Jan 20, 2014 at 04:28:45PM -0500, Jeff King wrote:

>   [1/2]: t/perf: time rev-list with UNINTERESTING commits
>   [2/2]: list-objects: only look at cmdline trees with edge_hint
> 
> Here's t/perf/p0001 output that shows the problem:
> 
>   0001.5: rev-list --objects $commit --not --all
>   fbd4a703^         fbd4a703                  HEAD
>   0.04(0.04+0.00)   0.28(0.27+0.00) +600.0%   0.04(0.04+0.00) +0.0%

Those numbers are on git.git. Obviously 600% is a lot, but 24ms is not.
However, the cost is a factor of the tree size times the number of refs.
For the "homebrew.git" repository stored at GitHub, which has ~28,000
refs (mostly pointing at pull-request tips in refs/pull), the numbers
are much more dramatic:

fbd4a703^         fbd4a703                   HEAD                 
0.50(0.46+0.02)   8.23(8.17+0.06) +1546.0%   0.50(0.48+0.01) +0.0%

-Peff

  parent reply	other threads:[~2014-01-20 22:29 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-01-20 21:28 [PATCH 0/2] performance regression in mark_edges_uninteresting Jeff King
2014-01-20 21:31 ` [PATCH 1/2] t/perf: time rev-list with UNINTERESTING commits Jeff King
2014-01-20 22:11   ` Jeff King
2014-01-20 22:32     ` Thomas Rast
2014-01-20 22:39       ` Jeff King
2014-01-20 21:32 ` [PATCH 2/2] list-objects: only look at cmdline trees with edge_hint Jeff King
2014-01-20 23:57   ` Duy Nguyen
2014-01-21  2:22     ` Jeff King
2014-01-20 22:29 ` Jeff King [this message]
2014-01-21  2:24 ` [PATCH v2 0/2] performance regression in mark_edges_uninteresting Jeff King
2014-01-21  2:25   ` [PATCH v2 1/2] t/perf: time rev-list with UNINTERESTING commits Jeff King
2014-01-21  2:25   ` [PATCH v2 2/2] list-objects: only look at cmdline trees with edge_hint Jeff King
2014-01-21 22:49     ` Junio C Hamano

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