On Sun, 2010-03-28, Stefan Fuhrmann wrote: > Hi devs, > > this is part of the delta_files() speedup patch series: > http://svn.haxx.se/dev/archive-2010-03/0604.shtml > > translate_chunk spends most of its time in a loop > looking for the next '$' or newline. The call to strchr > is excessively expensive since the 'interesting' string > is no longer than 3 chars. > > It is much more efficient to use a simple lookup table > (boolean array) that tells us whether a certain char > is 'interesting' or not. Since we call it for almost every > char in the file, the initialization overhead amortizes > within the first two lines of the respective file. > > Performance gain is ~9%: > > s~$ time ~/1.7-928181/svn export --ignore-externals -q $REPO/trunk /dev/shm/t > real 0m3.727s > user 0m3.189s > sys 0m0.542s > > ~$ time ~/1.7-patched/svn export --ignore-externals -q $REPO/trunk /dev/shm/t > real 0m3.410s > user 0m2.872s > sys 0m0.537s > > -- Stefan^2. > > [[[ > Optimize the search for 'interesting' characters that > control the keyword substitution. For details see > http:// ... > > * subversion/libsvn_subr/subst.c > (translation_baton): the 'interesting' member is now > a boolean array. > (create_translation_baton): adapt initialization code > (translate_chunk): eliminate call to strchr > > patch by stefanfuhrmann < at > alice-dsl.de > ]]]
This patch looks lovely, from the point of view of a read-through review. - Julian
