Re: [glean-dev] RFC: dsconfig matching changes

[Brian P. <br...@vm...>]

Allen Akin wrote:
> On Tue, Dec 08, 2009 at 06:54:40PM -0700, Brian Paul wrote:
> | In the case of readpixPerf, we only filter for rgb visuals.  Buf if 
> | the visual also has Z (or stencil) we do extra tests (and produce 
> | additional test results).  So, the ``A'' config and ``B'' config list 
> | were loosely filtered, but the test results are tied to specific 
> | configs.  The 'looseness' of the match() function causes us to compare 
> | results from disparate configs.
> 
> I guess I would have separated the tests -- one for color buffers, one
> for depth buffers, one for stencil buffers, and so on.  Not only would
> that have solved the match() problem, but it would have allowed other
> tests to depend on exactly the subset of readpixPerf tests that they
> need.
> 
> But that might not be expedient at this point.  So one thing that really
> makes sense to me is to ensure that exact matches take precedence over
> any partial match.  That ought to cover all the most common cases.
> 
> | Right.  But when the XIDs match AND ALL the other fields match, the 
> | configs should be identical (and the results comparable), even if the 
> | results come from different machines/drivers.
> 
> If ALL the other fields match, then the XID doesn't matter, right?  The
> configs should be identical from the GL's point of view?

Yes, except for the case I described below (there's some other 
attribute that glean's not aware of).


> | But in the case where there's many configs with identical fields, but 
> | different XIDs, the equal() test should consider the XID.
> | 
> | With GLX, for example, we can have two visuals which have identical 
> | attributes but one is TrueColor and the other is DirectColor.  The 
> | DrawingSurfaceConfig code doesn't consider visual classes.  This is 
> | where matching the XID is good.
> 
> If that really matters, then maybe Visual class should be added to the
> set of filterable attributes.  I don't think I ever encountered a system
> where the distinction between DirectColor and TrueColor mattered to the
> GL, but maybe there are examples nowadays.  I'm happy to defer to your
> judgement there.

I don't have time for any major changes now.  So here's a new patch 
which simply looks for an exact match before doing the error-based 
match algorithm.  It fixes the readpixPerf problem.

-Brian