[cairo] 1.1.6 to 1.2.0 performance

[David Turner]

James Cloos a écrit :
> John> Every time I run dot it opens 940 files in /var/cache/fontconfig
> John> just to resolve "Times-Roman" !
>
> That means that fc-cache found 940 (distinct) directories in its
> search path, cumulative over all runs since /var/cache/fontconfig
> was last cleared out.
>
>   
How on earth can you get 940 *directories* of fonts. Even the font CDs 
I've seen only
use a dozen directories, and they're packed with hundreds if not 
thousands of fonts.

It's be nice if James could send us the output of "fc-cache -r -v" to 
see the real numbers,
at least we wouldn't have to conjecture the problem.

I suspect some really horrible thing, like having "/usr/share" in the 
fontconfig search path,
and that most of the 940 cache files stored in /var/cache/fontconfig are 
essentially empty
because they correspond to directories that don't have any fonts in them.
> Fontconfig also keeps a single cache file in $HOME for any fonts
> not covered by the global per-dir cache files, so if you clean out
> /var/{lib,}/cache/fontconfig it will still work, but instead of
> open(2)ing and mmap(2)ing the cache files it will have to stat(2)
> every dir in the search path, see whether any are newer than the
> cache file, and check out every file in those that are newer to
> cache them.  So you don't win much.
>
>   
but doesn't stat-ing these 940 directories is going to be a *lot* faster 
than memory-mapping the
cache files that would be within them otherwise ?. I'm assuming that not 
all of them are going to
change a lot, so a single cache in $HOME could be a performance winner.
> Moving all of the fonts into a single directory, OTOH, would help --
> at least on a filesystem that hashes directories -- though it makes
> management harder.  
>
> I don't believe any other OS would do better with fonts spread out
> over 900+ directories.  
>
>   
An OS like MacOS X uses a single "font server" process. I'm pretty 
certain it wouldn't have
any problem with 900+ directories. Of course, this introduces a single 
point of failure, some
communication latency and startup slowness (unless caching is used); 
nothing is free :-)

Regards,

- David Turner
- The FreeType Project  (www.freetype.org)

PS: Apologies to the Cairo enthusiasts, this thread has little to do 
with your beloved library.


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