RT cuda and GPU power state

[super gnu]

during my recent overclocking adventures with the titan x, ive found out that RT (cuda apps in general?) set the gpu to power state p2, as opposed to P0

P0 is used for games and features the highest clocks for core and memory.

P2 is a more conservative set of clocks, particularly on the memory.


i assume this is deliberate so critical software running on cuda gets guaranteed stability.



however, it might be worth (if you didnt already) seeing if its possible to persuade RT to use power state P0 instead?

i dont know if this is possible or if it is baked into the NV drivers.

when i use NVinspector to manually match the ram clock in p2 to the one in p0 i get a healthy speedup in RT, and no issues.

this also explains why overclocking the titan X has some strange issues with RT (no speedup etc) since the "gaming" overclocking applications (precision, afterburn etc) only affect power state P0.

[vlado]

We are not doing anything specific to set the GPU either way and I don't know if this is possible for us to do so. If you render with iray, is it the same?

Best regards,
Vlado

[super gnu]

hm. never used iray.. i did a simple teapot on plane, and selected iray as the activeshade renderer, ticked the box next to my titan x to select it, and hit render.. seems to only use cpu though.

advice so i can test?

[vlado]

I think you can turn off the CPU... but other than that I have no idea either Does it change the state of your GPU?

Best regards,
Vlado

[super gnu]

no, but then the gpu stays on 0% usage, so obviously isnt even being used at all. i also dont see an option to disable cpu. only option to sselect number of coures.. maybe i set it to 0.

[super gnu]

hm.. ok so ive opened the mr log window, gives a load of cuda errors and refuses to render with my titan x:


IRAY 0.37 51 MB error: CUDA device 0 (GeForce GTX TITAN X): invalid device function (Failed to get function attributes)
IRAY 0.37 65 MB error: CUDA device 0 (GeForce GTX TITAN X): invalid device symbol (while launching CUDA renderer)
IRAY 0.37 65 MB error: CUDA device 0 (GeForce GTX TITAN X): Failed to launch renderer
IRAY 0.37 65 MB error: CUDA device 0 (GeForce GTX TITAN X): Device failed while rendering
IRAY 0.37 65 MB error: All devices failed: aborting render
IRAY 0.37 65 MB error: CUDA device 0 (GeForce GTX TITAN X): de-initialization failed
IRAY 0.38 50 MB error: CUDA device 0 (GeForce GTX TITAN X): invalid device function (Failed to get function attributes)
IRAY 0.38 64 MB error: CUDA device 0 (GeForce GTX TITAN X): invalid device symbol (while launching CUDA renderer)
IRAY 0.38 64 MB error: CUDA device 0 (GeForce GTX TITAN X): Failed to launch renderer
IRAY 0.38 64 MB error: CUDA device 0 (GeForce GTX TITAN X): Device failed while rendering
IRAY 0.38 64 MB error: All devices failed: aborting render



maybe ill try another cuda app instead :P

[auke]

Not sure if it will help, but you need 3ds Max 2016 for iRay to recognize the Titan X. It works fine in my system at least. Also setting cores/threads to 0 will indeed turn off CPU usage.

[super gnu]

ok arion benchmark also uses the p2 power state.

i suspect its the drivers detecting a cuda workload and selecting p2.. but maybe there is a way to override it. might be worth using your recent good relationship with nvidia to see if its possible


edit: yes im on 2014 so i wont be able to test with iray..

if its sufficiently interesting for you guys, you can easily check the p-state using nvinspector when rendering. displayed on the main interface.

[auke]

Just tested it and can confirm Titan X will go into P2 mode in 3ds Max with Vray, probably iRay as well. I can imagine it is a driver setting for using Cuda, as Cuda jobs tend to run a long time in contrast to games in which max power is only used for short periods (usually). Performance wise though, it still is impressive, the GPU still overclocks (just the normal Nvidia GPUboost, did not do editing myself) to 1177 MHz. Memory drops to 3500 MHz though.