Re: [PATCH 3/4] diffcore-pickaxe: further refactor count_match()

René Scharfe [off-list ref] writes:

I get this (Ubuntu 8.10 x64, Fedora 10 x64 using the same Linux repo,
Windows Vista x64 using a different Linux repo with the same HEAD on
NTFS and msysgit, numbers are the elapsed time in seconds, best of five
runs):

                           Ubuntu  Fedora  Windows
   v1.6.2-rc2                8.14    8.16    9.236
   v1.6.2-rc2+[1-4]          2.43    2.45    2.995
   v1.6.2-rc2+[1-4]+memmem   1.31    1.25    2.917
   v1.6.2-rc2+[1-3]+memmem   1.51    1.16    8.455

Ubuntu has glibc 2.8, while Fedora 10 has glibc 2.9, with a new and more
efficient memmem() implementation.  On Windows, we use our own naive
memmem() implementation.

Yeah, what does glibc use these days?  Some variant of Boyer-Moore?

So using memmem() is worthwhile.  And providing a better fall-back
version in compat/ can speed up this particular case to the point where
the fourth patch becomes moot.

Hmm, gnulib (http://git.savannah.gnu.org/gitweb/?p=gnulib.git;a=summary)
contains all parts ready for copy & paste, licensed under the GPL 2 or
up.  That won't cause problems with the libgit2 relicensing effort, as
memmem()  won't end up in there, right?

Correct.