Re: [Tuxmath-devel] Further performance improvement with more caching mechanisms

[Tim H. <ho...@wu...>]

Hi Wenyuan,

This is good, careful work. I think your willingness to change your plans is 
admirable, and the half-second delay seems very livable, a big improvement on 
the previous 2s. Long live profiling! :-).

Best,
--Tim

On Wednesday, July 21, 2010 06:26:11 pm Wenyuan Guo wrote:
> Hi all,
> 
> With more careful profiling of the program, I found my earlier theory
> to be wrong: I thought the delay when switching resolution mainly came
> from HDD delay. This component turns out to be minor, thanks to OS
> caching. The following two components are much more significant:
> 
> 1. Surprisingly, the librsvg function that determines the dimension of
> an input SVG image file takes substantial time. I had thought that it
> ought to be as simple as to locate the relevant strings from the SVG
> file involving only minimum parsing efforts. In any case, I have build
> an in-memory caching table to store dimensions of SVG files seen
> before to minimize this performance penalty to once per file for each
> session.
> 
> 2. The PNG function to parse input file into SDL surface is the second
> contributor to the delay, although smaller than 1. I have built
> another in-memory caching mechanism for these SDL surfaces, with
> reference copying instead of actual data copying. This assumes that
> all loaded SDL surfaces are never modified, which seem to be the case
> for tuxmath. This is faster and more memory efficient.
> 
> With the additional caching, pressing F10 to switch resolution takes
> only 0.5s, compared with about 2s before. Given this small delay, I
> have scratched the multithreading mechanism implemented before, which
> is no longer necessary. Moreover, the multithreading functions still
> have mysterious bugs. There are too many rendering functions that have
> global variable and I/O conflicts. It is extremely difficult to
> identify all race conditions between them at this point.
> 
> Cheers
> Wenyuan
> 
> ---------------------------------------------------------------------------
> --- This SF.net email is sponsored by Sprint
> What will you do first with EVO, the first 4G phone?
> Visit sprint.com/first -- http://p.sf.net/sfu/sprint-com-first
> _______________________________________________
> Tuxmath-devel mailing list
> Tux...@li...
> https://lists.sourceforge.net/lists/listinfo/tuxmath-devel