On Mon, Apr 25, 2005 at 03:28:27PM +0100, Philip Martin wrote:
> > $ ab -clkao- [/tmp/diff_file_diff3] time perl diff.t
> > _p_svn_diff_t=SCALAR(0x804d23c) at diff.t line 4.
> > 158.366u 1.264s 3:00.50 88.4% 10+16118k 0+0io 0pf+0w
> >
> > But with /usr/bin/diff3:
> >
> > $ ab -clkao- [/tmp/diff_file_diff3] time diff3 bad-empty.csv bad-local.csv
> > bad-new.csv > /dev/null
> > 0.455u 0.055s 0:00.64 78.1% 48+9124k 0+0io 0pf+0w
>
> This is likely to be because GNU diff uses a number of heuristics to
> shortcut the full diff algorithm and Subversion's diff implementation
> doesn't do this. Without the heuristics GNU diff is likely to take
> much longer. diff3 doesn't appear to allow one to disable the
> heuristics but diff has the --minimal switch, try
>
> $ diff --minimal bad-local.csv bad-new.csv
81.712u 0.288s 1:41.44 80.8% 56+9008k 0+0io 0pf+0w
> $ diff bad-local.csv bad-new.csv
$ ab -clkao- [/tmp/diff_file_diff3] time diff bad-local.csv bad-new.csv > /dev/null
0.102u 0.007s 0:00.11 90.9% 61+8630k 0+0io 0pf+0w
You are right. So is there any reason that we shouldn't have such
heuristics?
Cheers,
CLK
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Received on Mon Apr 25 17:42:06 2005