Re: [Lcms-user] Threading performance in LCMS2

[Robin W. <rob...@ar...>]

On 14/05/2013 09:20, Richard Hughes wrote:
> Other than profiling, how do we know if it's chosen a built-in version
> rather than the generic version?

I initially used profiling, but then I added some code to capture what 
transforms were used. This is also on the same branch I pointed you at 
before. A direct link is:

https://github.com/robinwatts/Little-CMS/commit/585c6191363a0989cb80e628529f985bf298c95a

Should be straightforward (enable the 'GATHER_TRANSFORM_STATS' #define 
in the patch) and run your code. On exit it will dump the stats to stderr.

> I see, https://github.com/robinwatts/Little-CMS/blob/artifex/src/cmsxform.h
> -- that looks pretty magic, is there no way to do that without the
> #preprocessor trickery?

Not without expanding out every case separately - exactly what I wanted 
to avoid. You shouldn't need to understand the implementation in 
cmsxform.h though - you just need to look at cmsxform_extras.c for how 
to use it.

>> He did however point out that I could recast the code slightly as a
>> plugin for lcms 2. This gives the same benefits without polluting the
>> internals of the library itself. I plan to do this at some point, but I
>> have not got round to it yet.
>
> Yes, that would be awesome.

The new lcms is due in June I think. We'll probably pull that into gs 
and recast our optimisations as a plugin lib then.

HTH,

Robin