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From: Jeff King <peff@peff.net>
To: git@jeffhostetler.com
Cc: git@vger.kernel.org, gitster@pobox.com,
	Jeff Hostetler <jeffhost@microsoft.com>
Subject: Re: [PATCH v1] diffcore-rename: speed up register_rename_src
Date: Tue, 18 Apr 2017 21:32:15 -0400	[thread overview]
Message-ID: <20170419013214.q35jarvmk5jhqdyi@sigill.intra.peff.net> (raw)
In-Reply-To: <20170418194421.22453-2-git@jeffhostetler.com>

On Tue, Apr 18, 2017 at 07:44:21PM +0000, git@jeffhostetler.com wrote:

> From: Jeff Hostetler <jeffhost@microsoft.com>
> 
> Teach register_rename_src() to see if new file pair
> can simply be appended to the rename_src[] array before
> performing the binary search to find the proper insertion
> point.

I guess your perf results show some minor improvement. But I suspect
this is because your synthetic repo does not resemble the real world
very much. You're saving a few strcmps, but for each of those files
you're potentially going to have actually zlib inflate the object
contents and do similarity analysis.

So "absurd number of files doing 100% exact renames" is the absolute
best case, and it saves a few percent.

I dunno. It is not that much code _here_, but I'm not excited about the
prospect of sprinkling this same "check the last one" optimization all
over the code base. I wonder if there's some way to generalize it.

-Peff

  reply	other threads:[~2017-04-19  1:32 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-04-18 19:44 [PATCH v1] diffcore-rename speedup git
2017-04-18 19:44 ` [PATCH v1] diffcore-rename: speed up register_rename_src git
2017-04-19  1:32   ` Jeff King [this message]
2017-04-19  2:45     ` Junio C Hamano
2017-04-19  2:56       ` Jeff King
2017-04-19  3:18         ` Jeff King
2017-04-20 14:00           ` Jeff Hostetler
2017-04-20 16:13             ` Jeff King
2017-04-20 18:08               ` Jeff Hostetler
2017-04-20 18:34                 ` Jeff King
2017-04-21  1:19                   ` Junio C Hamano
2017-04-20 10:40     ` Johannes Schindelin
2017-04-20 15:50       ` Jeff King

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