[Piglit] [PATCH 6/7] ARB_pipeline_statistics_query (frag): basic test

[Ben Widawsky]

On Sat, Feb 14, 2015 at 02:07:32AM -0500, Ilia Mirkin wrote:
> On Sat, Feb 14, 2015 at 1:54 AM, Ben Widawsky
> <benjamin.widawsky at intel.com> wrote:
> > +static struct query queries[] = {
> > +       {
> > +        .query = GL_FRAGMENT_SHADER_INVOCATIONS_ARB,
> > +        .name = "GL_FRAGMENT_SHADER_INVOCATIONS_ARB",
> > +        .min = TEST_WIDTH * TEST_HEIGHT / 2,
> > +        .max = 0xffffffff},
> > +       /* XXX:
> > +        * Intel hardware has some very unpredictable results for fragment
> > +        * shader invocations. After a day of head scratching, I've given up.
> > +        * Generating a real min, or max is not possible. The spec allows this.
> > +        * This will also help variance across vendors.
> > +        */
> 
> Is there a working theory as to how this could be less than width *
> height? Does it count 1 per quad? (Or how it could be much more than
> width * height... I can see edges getting processed unnecessarily,
> but... max_int seems high.)

No working theory on min, but I figured if we're going to fudge the max, we may
as well fudge the min. What would you like as a max? I can show you hardware
which generates way more invocations than anything I can contrive. 1440
invocations for an 8x8.

-- 
Ben Widawsky, Intel Open Source Technology Center