[PATCH 14/20] glamor: stub out lines

[Markus Wick]

Am 2014-03-24 06:28, schrieb Keith Packard:
> 1: intel-glamor.perf
> 2: intel-glamor-line.perf
> 
>        1                 2                 Operation
> ------------   -------------------------   -------------------------
>     471000.0    231000000.0 (   490.446)   1-pixel line
>     297000.0    209000000.0 (   703.704)   1-pixel line segment

Nice speedup.

>     456000.0     12200000.0 (    26.754)   10-pixel line
>     384000.0     10600000.0 (    27.604)   10-pixel line segment
>     463000.0    134000000.0 (   289.417)   10-pixel horizontal line 
> segment
>     460000.0      8770000.0 (    19.065)   10-pixel vertical line 
> segment

>     371000.0      1120000.0 (     3.019)   100-pixel line
>     325000.0      1060000.0 (     3.262)   100-pixel line segment
>     459000.0      6550000.0 (    14.270)   100-pixel horizontal line 
> segment
>     354000.0       851000.0 (     2.404)   100-pixel vertical line 
> segment

>     218000.0       296000.0 (     1.358)   500-pixel line
>     148000.0       289000.0 (     1.953)   500-pixel line segment
>     467000.0      4020000.0 (     8.608)   500-pixel horizontal line 
> segment
>     160000.0       177000.0 (     1.106)   500-pixel vertical line 
> segment

I don't get it, why are horizontal lines so much faster than vertical 
ones? This sounds like software rasterization for GL_LINES.
Should this be treated as a mesa bug or shall we write a workaround 
using triangles?