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Roman (kOsMos)
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Nov 14 2015, 4:27 PM (204 w, 5 d)

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May 27 2016

Roman (kOsMos) added a comment to T48523: completely freezes when fbx file is imported.

I tried it, and it froze for about 5 seconds, then it unfroze, but I dont see any mesh that was imported.
What is supposed to be inside the file?

May 27 2016, 5:21 AM · Add-ons
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Nothing was changed from my side,
Before and after installing driver 368.22: 1 min 29 sec
Card: nVidia GTX GeForce Titan X
Tiles: 128X128
Blender version: 2.77a

May 27 2016, 5:11 AM · BF Blender

May 26 2016

Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

@Sergey Sharybin (sergey)
Just downloaded latest from builder.blender.org
Definitely faster on the 980ti:
Mikes 2.7 scene: 1:06!
50 seconds faster than the official build it seems for me.

May 26 2016, 3:28 PM · BF Blender
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

There is no reason to paste each occasion when NVidia support accepts your issue, we already know that they accepted it. Respect others time and time of developers who'll need to scroll over all the comments here trying to extract meaningful information.
Anyway, did anyone try 368.22 driver? From some feedback seems it brings performance improvements.

May 26 2016, 1:57 PM · BF Blender

May 25 2016

Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Response Via Email (Troy) 05/24/2016 04:34 PM

May 25 2016, 4:00 AM · BF Blender

May 23 2016

Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Ive been communicating with Nvidia Support for several days now, I also made a video for their dev team exactly how to reproduce the issue in win8.1 and win 10. This is the last worthy response I received from them. Supposedly the error has something to do with WDDM 2.0 since thats what windows 10 uses. Windows 7/8/8.1 use WDDM 1.1/1.2/1.3. yw :D

May 23 2016, 4:40 PM · BF Blender

May 17 2016

Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Got under 20s with Titan X in Windows 8.1. Tiles 512x512 seem to give best result.

Are you talking about the new BMW scene with two cars (BMW27.blend)?
There are lots of reports for this scene to take more than one minute with blender 2.77, Linux and a single Titan X. On my system I get 1:06 (which is not significantly better than the results with a 760ti). 20s would be really satisfying.
Update: I just did a test on Win 8.1 Enterprise on my Titan X (driver version 365.19): 1:08 min. There is no big difference between Linux and Win 8.1 on my computer.

May 17 2016, 11:46 PM · BF Blender
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Roman: Octane is a CUDA-only render engine, it probably uses much smaller kernels - its a complete different architecture.
Further: I have witnessed Sergey doing tests, and he did an incredible thorough job, spending days on it.
This is not in our hands anymore.
The error is in the Nvidia drivers for Windows 10. We cannot fix this. Tell Nvidia. Tell Microsoft. Or use Linux or Windows7.

May 17 2016, 3:48 AM · BF Blender
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

@Lee Jones (moony) I am beginning to believe there is a memory component to this as well. In all our tests here (Moony, we have the same types of results as you, showcasing a marked slowdown in 2.77 that is not present in 2.75 or 2.76 while utilizing the same drivers) I've noticed that the Memory Controller Load on the TitanX is significantly reduced while in 2.77 that is not present in other renders. So I can independently verify your results. Is it possible that GPUs which contain higher vRAM (6GB and over) are experiencing some kind of memory leak or underutilization due to some kind of RAM limit? I'm a bit out of my depth on this, clearly.
@Sergey Sharybin (sergey) Thanks for bringing some order back to this report. :) I do want to note that the Smoke on GPU I believe is related to this problem, not independent from it, as in that environment the 780ti was exponentially faster than the TitanX when rendering smoke. I believe volumetric calculations exacerbate this problem we're reporting here, though the subject of the rendering is slightly different. We're still seeing the 780ti outpreform the TitanX every single time. That is, whenever we can get it to render as the 708ti's 3GB vRAM limit is rather limiting these days. :)
I did not see the earlier build you had, Sergey, for testing out the GPU calculations. If you'd like I can run some tests here on the TitanX to see if the results would be similar to what Adam yielded. Where can I find that build?
Perhaps we just need to pool together to buy the foundation a TitanX. :)

May 17 2016, 12:06 AM · BF Blender

May 16 2016

Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

I'd like to also add that Windows 8.1 works too, Just as good as Windows 7.

May 16 2016, 7:05 PM · BF Blender
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

@Andy (AndyZ), developers are silent because they are kind of in the middle of something. It is NOT a forum, flooding report would not make developers more active and will not lead to a faster bug fix.
Please don't use the bug tracker as a user-to-user communication, use BA forum instead and only put really helpful information here.
@Alicja (Alicja), this is out of the scope of this report.
@Lee Jones (moony), you can always gain some %% of speedup by fine-tuning parameters for a particular hardware. That's NOT what we're troubleshooting. While you say there are more optimal tile size it'll be more optimal for all the OSes (since it depends on hardware, basically number of threads on the GPU). Tweaking tile size will NOT change the fact that Windows 10 renders 3 times slower than Linux or Windows 7.
@Roman (kOsMos), We don't have Titan X here in the studio, but i can not confirm such a slowdown with 980Ti (which is the same Compute Capability 5.2) we do have here, both 2.76 and 2.77a behaves same slow.

To conclude

So what did a while ago was we've created a special build which avoids ANY of CPU interaction during GPU rendering, avoiding any possible latency (tile was fully sampled on GPU, only final tile result was reported back to CPU). This way we're sure we're loading GPU as much as possible.
This test was tested by @Adam (-pXd-) (only by him btw, nobody else even dared to do tests which are needed for further investigation). This did not give any measurable difference in the render time (if i read timing correct and comparing it to proper baseline). This means the root of the issue of render time difference between various platforms is not the way how we launch CUDA kernels, root of the issue is inside of the driver of OS itself.
We also went couple of versions back and compared render times between Windows 10 and Linux, and Linux was consistently faster (around 3 times) on the same hardware. (And as we tested before, Windows 7 was quite on the same level as Linux). So we can not confirm any claims that sm_52-based cards were faster in previous releases.
We also tested regular 980 card (NOT a Ti) on Windows 10 and Linux in the same machine. And surely enough it was much slower in Windows 10 again.
All this currently leads us to a conclusion that it's something fundamentally broken in either Windows 10 itself or NVidia's driver for this platform. This isn't something we can look ourselves (well, we could, but MS is not really happy about reverse-engineering their products ;). For until some major update happens from either Microsoft or NVidia sides i don't see what else we can do here currently.
P.S. Comparing Cycles to IRay is not really legit. IRay is specifically designed and optimized for CUDA architecture. Additionally, as far as i can see nobody compared IRay on Win10 and Linux, so you can't say IRay's performance is on it's maximum either, it might be same 3x times faster on Linux.
P.P.S. Again, even inoptimal design of Cycles Kernel does not cancel the fact that it is only slow on Windows 10 and that's it's much-much faster on Win7 and Linux.

May 16 2016, 10:34 AM · BF Blender
Roman (kOsMos) added a comment to T45093: Cycles: NVidia GTX 980 Ti rendering at 1/3rd speed of NVidia GTX 980 the same machine?.

Obviously there is problem with cycles. Horrible GPU render performance on GTX Titan X with v2.77a. Basically Titan X is 127% slower than 780 Ti when rendering Mike Pan's BMW scene. But with v2.76 it is only 32% slower, still it should not be slower! I am not super expect but the first thing that comes to mind is most likely bad code in the kernel file kernel_sm_52.cubin OR the larger VRAM on 980ti and Titan X.

May 16 2016, 2:00 AM · BF Blender

Nov 15 2015

Roman (kOsMos) added a comment to T43310: GPU memory explode since version 2.73.

Is there a working beta of the split kernel? ETA?

Nov 15 2015, 3:25 AM · GPU / Viewport, BF Blender
Roman (kOsMos) added a comment to T43310: GPU memory explode since version 2.73.

I just rendered this bench test scene BMW27.blend (http://blenderartists.org/forum/showthread.php?239480-2-7x-Cycles-benchmark-%28Updated-BMW%29&highlight=2.7+benchmark), on v2.71 and v2.76, got identical times(1:27) in both versions but v2.76 used 1300MB VRAM and v2.71 used 800MB. You said this is because volume rendering has been added to v2.72 and up but both images look identical so why is it eating up 500MB more VRAM for some feature that I am not even using?

Nov 15 2015, 1:16 AM · GPU / Viewport, BF Blender
Roman (kOsMos) added a comment to T43310: GPU memory explode since version 2.73.

So by adding volume rendering on GPU it uses up twice as much VRAM? Still a simple cube like this should not take up 1/3rd of VRAM. CPU rendering just takes less than 3MB of system RAM to render the same scene but 1,150GB VRAM on GTX780Ti seems a bit extreme dont you agree? Octane just uses under 300MB for comparison, 4x less than Cycles in Blender v2.72-v2.76 to render the same scene. Even with the Quadro K2200 378MB is high. Seems like there is a lot of VRAM being wasted somewhere and the code still has room for performance optimizations.

Nov 15 2015, 12:29 AM · GPU / Viewport, BF Blender

Nov 14 2015

Roman (kOsMos) added a comment to T43310: GPU memory explode since version 2.73.

I ve done multiple render test's with the basic cube scene as far as v2.66 to the latest v2.76 and noticed with GPU-Z that with each new release Cycles uses more and more VRAM then what it actually reports inside Blender while rendering.

Nov 14 2015, 7:00 PM · GPU / Viewport, BF Blender