Rasterisation patterns of the Haswell GPU

http://www.g-truc.net/post-0597.html

by willvarfar • 13 years ago

64 13 13 years ago

g-truc.net

trafficlight• 13 years ago

That's cool, I think. Do you have any links to examples from other CPUs/GPUs?

willvarfar• 13 years ago

(Poster, not author)

(There are Kepler and Southern Islands patterns on the same page for comparison)

I am trying to internalise this for CUDA and OpenCL kind of mechanical sympathy optimisation.

kevin_rubyhouse• 13 years ago

I don't understand the significance of this... Can somebody explain it to me like I'm 5 or provide a source for me to understand this more?

ygra• 13 years ago

No expert here (heck, I've done maybe 5 minutes of OpenGL so far).

It reads like they use a special pixel shader to color each pixel of a texture in a more of less unique color based on when the pixel (or maybe block) was scheduled to be shaded (I'm guessing here based on the atomic counter bit). This yields a texture that shows the order in which pixel shaders are run on a texture. This seems to be different for different GPUs and architectures (unsurprisingly) and also seems to give insights into how certain things are implemented.

But that's all just a bit of guessing. Someone else might be able to give an actual explanation.

nobodysfool• 13 years ago

Yea well reading it closely, the red's value is what you see with the highest frequency of change. You can see that red increases then increments green, then starts over again at zero, so by looking closely at red, you can see where the computations stop and start over again, thus giving you the reds pattern. As to what it means, who knows.

lbenes2• 13 years ago

Are these atomic counters related to the atomic object feature that was promised with OGL 3.0 and then dropped? Is there a template model now in OGL or is it using a different method to create immutable objects across multiple threads?

Please excuse my ignorance as I haven’t looked at OpenGL since 3.0 was released in 2006. Now SteamOS has piqued my interest in OGL again.

Edit: grammar. Thanks jonah! After some googling, it looks like atomic counters are not the same as the promised atomic objects, but seems OGL 4.0+ has nearly closed the feature gap with DX11.

jonah3• 13 years ago

https://www.vocabulary.com/articles/chooseyourwords/peak-pee...

http://www.thefreedictionary.com/pique

(Nothing against you in particular, just a very common misuse.)

Amadou2• 13 years ago

From your second link:

2. To provoke; arouse: The portrait piqued her curiosity.

oofabz• 13 years ago

It is also interesting to see video of these rasterization patterns. The pattern is not exactly the same from frame to frame.

Nvidia: http://www.youtube.com/watch?v=WFx6StqpRdY

AMD: http://www.youtube.com/watch?v=WnUS8kzA3dI

Rasterisation patterns of the Haswell GPU

Related Stories