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giga rays on intel phi

Posted: Thu Sep 05, 2013 9:18 am
by mpeterson
Image

hallo, we just released our tracing kernels for intel phi. enclosed a simple test scene. it runs at
1.2 grays/s on latest 7xxx series ! btw: it is also around 2x faster than intels embree 2.0.

maik

Re: giga rays on intel phi

Posted: Thu Sep 05, 2013 10:53 am
by voxelium
Impressive performance! Are your kernels publicly available somewhere?

Re: giga rays on intel phi

Posted: Thu Sep 05, 2013 1:20 pm
by graphicsMan
Interesting. Do you have numbers for diffuse interreflections?

Re: giga rays on intel phi

Posted: Fri Sep 06, 2013 1:44 am
by straaljager
Looks like Whitted ray tracing, not even ao. Are you sure this quality is still relevant today?

Re: giga rays on intel phi

Posted: Fri Sep 06, 2013 8:17 am
by jbikker
Regardless of ray distribution, I think 1.2G is amazing, and it's very cool that you managed to break the 1G barrier! Wald wrote in his slides for a SIGGRAPH course a few years ago 'ray tracing performance is expressed in *millions of rays*, not thousands'. Looks like this has to be adjusted for today. :)
Also, for that kind of scenery, a Titan can perhaps reach 500M, so the phi appears to be vastly better for ray tracing. That's a good thing if you want to sell a new architecture.

Re: giga rays on intel phi

Posted: Mon Sep 09, 2013 9:11 am
by mpeterson
@graphicsman: not yet. more "in-deep" test for any kind if distribution will come in the next weeks.
just ordered a titan to see and compare different scenarios. pt results as soon as it arrives.
this is a nice research project. we have to build a system that can trace 256 rays/pixel@1080p > 10fps
for a given set of shaders. now we have to select hw that looks most promising when running our
kernels on top.

mp

Re: giga rays on intel phi

Posted: Mon Sep 09, 2013 6:53 pm
by graphicsMan
256 eye rays or total rays?

Re: giga rays on intel phi

Posted: Mon Sep 09, 2013 7:17 pm
by jbikker
Even with total rays, that's like 5G, minimum. You intend to use 4 phi's?
By the way, I'm not sure how the phi will behave with divergent rays; CPUs tend to suffer badly if you can't use large packets anymore (as in: 10x slower). GPUs do much better in those situations. If you expect to use a random ray distribution, you may want to look into that.

Re: giga rays on intel phi

Posted: Mon Sep 09, 2013 11:03 pm
by voxelium
jbikker wrote: By the way, I'm not sure how the phi will behave with divergent rays
In my experience, the Phi handles incoherent rays pretty well: https://twitter.com/attila_afra/status/ ... to/1/large

Re: giga rays on intel phi

Posted: Tue Sep 10, 2013 7:39 am
by jbikker
Do you happen to have that car scene available? I managed to find a similar model of the car online, but I would love to test the exact scene on a Titan.