Intel ( i845G ) profiling

Simon Thum simon.thum at
Thu Mar 6 10:39:51 PST 2008

> anyway - i'm glad its useful. keep up the benchmarking and lets hope not too
> long from now most chipsets and drivers are running smoothing with xrender.
If one could make or point me to some short description on how to 
measure, I'd glady devote some of my spare time. I still use some 
howebrew XAA hack to evade the worst cases, even though EXA is faster in 

> ten i can get onto my next favorite game and bitching about the quality of the
> rendering ( e.g. filtered downscaling in xrender :):) )
You've accidentially played my favourite game :) Thus, feel free to 
ignore my ramblings.
Filtered downscaling: I think it's broken (usually). People tend to 
attribute quality shortcomings to the poor frequency response of the box 
filter, but I think that in the vast majority of cases the true source 
is the broken way of dealing with it. The supersampling/box filter/about 
most stuff has to be performed in an intensity-linear space to yield a 
correct result. See (at end of part 1)

IOW, supersampling or filtering without prelinearization is plain wrong. 
This stems from the fact that addition of gammacoded values has no 
pysical counterpart, strictly speaking, it is not defined. This won't 
cause the computer to blow up of course, but output quality suffers. 
Prefiltering successfully hides this in many cases, but makes matters 
worse for others. Including glyphs, IMO.

If you knew that, as your name implies, I'm sorry for bugging you and 
being a nuisance in general. But please, at least give it a shot before 
implementing the 1000th well-meant workaround.

>> If someone wants me to profile something different, please feel free to
>> ask :)
As I wrote you just before I read this, I've got a very similar R280. FF 
2/3 (tabs) and thunderbird (scrolling the inbox) are unuseable to me w/EXA.
Maybe you can profile this?

Thanks a lot,


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