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svn diff optimization to make blame faster?

From: Johan Corveleyn <jcorvel_at_gmail.com>
Date: Wed, 18 Aug 2010 00:59:21 +0200

Hi devs,

While "Looking to improve performance of svn annotate" [1], I found
that the current blame algorithm is mainly client-side bound, and that
most of its time is spent on "svn diff" (calls to svn_diff_file_diff_2
from add_file_blame in blame.c). Apart from avoiding to build
full-texts and diffing them altogether (which is subject of further
discussion in [1]), I'm wondering if optimization of "svn diff"
wouldn't also be an interesting way to improve the speed of blame.

So the main question is: is it worth it to spend time to analyze this
further and try to improve performance? Or has this already been
optimized in the past, or is it simply already as optimal as it can
get? I have no idea really, so if anyone can shed some light ...

Gut feeling tells me that there must be room for optimization, since
GNU diff seems a lot faster than svn diff for the same large file
(with one line changed) on my machine [1]. But maybe svn's diff
algorithm is purposefully different (better? more accurate? ...) than
GNU's, or there are specific things in the svn context so svn diff has
to do more work.

Any thoughts?

[1] http://svn.haxx.se/dev/archive-2010-08/0408.shtml
Received on 2010-08-18 01:00:00 CEST

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