On Sun, Aug 22, 2010 at 4:02 PM, Branko Čibej <br...@xbc.nu> wrote: > On 18.08.2010 00:59, Johan Corveleyn wrote: >> 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? >> > > svn_diff uses basically the same algorithm as GNU diff but implemented > slightly differently and IIRC it doesn't have some of GNU diff's > optimizations. I'm sure it can be speeded up, but haven't a clue about > how much.
Ok, thanks. In the meantime I saw that there is not that much difference anymore between GNU diff and svn_diff, after running the latter from a release build, and disabling my anti-virus (which makes me wonder why my anti-virus slows down svn_diff (impact when opening the modified datasource), but not on GNU diff). There may still be some slight speed difference (enough to be significant for a blame operation doing 100's or 1000's of diffs), but not that much as I thought at first. So I don't think I'm going to spend more time on trying to speed up svn_diff (also, I'm not really an expert at optimizing C code, so ... I'll leave that to others :-)). Cheers, -- Johan
