[Mesa-dev] [PATCH 0/3] Pixman for Mesa

[Juha-Pekka Heikkila]

On 28.08.2014 19:18, Jason Ekstrand wrote:
> Juha-Pekka,
> I'll try and look at the actual patches here next week.  For now, a
> couple quick comments.
> 
> 
> On Thu, Aug 28, 2014 at 5:51 AM, Juha-Pekka Heikkila
> <juhapekka.heikkila at gmail.com <mailto:juhapekka.heikkila at gmail.com>> wrote:
> 
>     Here is new version of my patch set for using Pixman in Mesa
>     for texture format conversions, mostly complete rewrite after recent
>     changes in src/mesa/main/texstore.c. This set does not cause
>     regressions in Piglit quick set on SNB.
> 
>     Here are some timings I came up from with this set when running
>     glTexImage2d in a loop (on SNB, IVB was comparable):
> 
> 
> Did you test this on HSW?  How did it look there?  Also, please provide
> the type, format, and internal format that you're using in your tests. 
> differences between format and internal format can make a huge
> difference on what path you hit.

Alas I have no HSW to test with. All I can use is dekstop SNB and mobile
IVB.

> 
>                                           No Pixman       Pixman     %
>     GL_UNSIGNED_INT_8_8_8_8,GL_BGRA     2816.648926 <tel:2816.648926> 
>     2148.145020  0.76
>     GL_UNSIGNED_SHORT_5_6_5,GL_RGB     19560.732422  2062.745117  0.11
>     GL_UNSIGNED_SHORT_5_6_5_REV,GL_RGB 19525.605469  4035.947998  0.21
> 
> 
> I'm a little skeptical of the 8888 numbers.  In my testing on my HSW
> laptop, the C path we have now was very close to the SSSE3 fast-path I
> cooked up to test against.  There could be a difference in memory
> bandwidth for certain instructions though.  That's why I'd like to see
> HSW, SNB, and IVB numbers side-by-side for that one.
> 

I think faith based computing is always a bit iffy. I'll send you my
simplistic test in email so you can run the numbers yourself. My test is
lot of glue and cut'n'paste but I don't see anything in it which would
cause the timings to go somehow repeatedly wrong for one particular
format. Type'n'format used you can see from the test and in the patches
you notice list of internal formats I made support for is not very
numerous. List of most potential formats to support came from Eero who
had logged what kind of texture formats some games use.

/Juha-Pekka