From: Jeff King <peff@peff.net>
Date: Wed, 19 Apr 2017 01:32:15 GMT
Subject: Re: [PATCH v1] diffcore-rename: speed up register_rename_src
Message-ID: <20170419013214.q35jarvmk5jhqdyi@sigill.intra.peff.net>
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