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Daz 4.12 Iray reports a lot less free VRAM than Task Manager

emu42emu42 Posts: 50
in Technical Help (nuts n bolts)

Hello all,

so I have tried to render a rather large scene in 4.12 hoping it would fit into VRAM. I have an RTX 2080 Ti with 11GB and according to Windows task manager at about 10GB should be available before I start rendering.

Then this happens:

2019-08-25 17:36:49.675 Iray [INFO] - IRAY:RENDER ::   1.0   IRAY   rend info : Initializing local rendering.
2019-08-25 17:36:49.755 Iray [INFO] - IRAY:RENDER ::   1.0   IRAY   rend info : Rendering with 1 device(s):
2019-08-25 17:36:49.755 Iray [INFO] - IRAY:RENDER ::   1.0   IRAY   rend info :     CUDA device 0 (GeForce RTX 2080 Ti)
2019-08-25 17:36:49.756 Iray [INFO] - IRAY:RENDER ::   1.0   IRAY   rend info : Rendering...
2019-08-25 17:36:49.757 Iray [VERBOSE] - IRAY:RENDER ::   1.4   IRAY   rend progr: CUDA device 0 (GeForce RTX 2080 Ti): Processing scene...
2019-08-25 17:36:50.553 WARNING: ..\..\..\..\..\src\pluginsource\DzIrayRender\dzneuraymgr.cpp(305): Iray [ERROR] - IRAY:RENDER ::   1.6   IRAY   rend error: Unable to allocate 6033795708 bytes from 5279988940 bytes of available device memory

... and Iray falls back to CPU rendering.

So, Iray attempts to allocate 6GB but somehow there are only 5.2GB available. I think I'll be able to optimize this particular scene and make it work, but I would still like to know why this is happening.

Any idea why Iray would report roughly only half as much available VRAM as the Task Manager?

 

Comments

  • kenshaw011267kenshaw011267 Posts: 3,805

    Are you using the 2080ti to drive a 4k display or something? Did you have another render open at the time? task manager doesn't report available VRAM accurately but more than 6Gb used seems strange.

  • emu42emu42 Posts: 50
    kenshaw011267 said:

    Are you using the 2080ti to drive a 4k display or something? Did you have another render open at the time? task manager doesn't report available VRAM accurately but more than 6Gb used seems strange.

    Actually, two 4k displays. :)

    No other renders. I had pretty much all other applications closed at the time. According to the task manager, Daz itself and and DWM.exe each occupied at about 500MB and the rest was just small-fry with <100MB in total.

    I think I'll try connecting just one display and setting its resolution to 1080p to see whether that makes a difference.

  • PadonePadone Posts: 3,796

    I'd suggest using gpu-z to test the vram usage, afaik the log can't be trusted, and the task manager isn't that smart too although in my system it seems to work fine enough.

  • kenshaw011267kenshaw011267 Posts: 3,805
    emu42 said:
    kenshaw011267 said:

    Are you using the 2080ti to drive a 4k display or something? Did you have another render open at the time? task manager doesn't report available VRAM accurately but more than 6Gb used seems strange.

    Actually, two 4k displays. :)

    No other renders. I had pretty much all other applications closed at the time. According to the task manager, Daz itself and and DWM.exe each occupied at about 500MB and the rest was just small-fry with <100MB in total.

    I think I'll try connecting just one display and setting its resolution to 1080p to see whether that makes a difference.

    2 4k displays is going to put a serious dent in your VRAM.

  • fastbike1fastbike1 Posts: 4,078

    I have a monitor set for 1080P and a second at 1440. With Studio loaded and Chrome plus a couple of Exploroer windows, I typically have <500MB of VRAM used prior to starting a render.

  • emu42emu42 Posts: 50

    So, with just one screen set to 1080p, I could reduce VRAM usage by ~250MB. Both, task manager and Daz log, show this change.

    Padone said:

    I'd suggest using gpu-z to test the vram usage, afaik the log can't be trusted, and the task manager isn't that smart too although in my system it seems to work fine enough.

    I'll give that a try.

  • JonnyRayJonnyRay Posts: 1,744
    Padone said:

    I'd suggest using gpu-z to test the vram usage, afaik the log can't be trusted, and the task manager isn't that smart too although in my system it seems to work fine enough.

    I was just going to suggest the same thing. Windows Task Manager has been notorious for not being able to properly query devices like GPUs. One could argue where the failure is (Windows, Drivers, Device itself), but it definitely seems like GPU-Z (download link) is much more accurate. Just don't pull your hair out when Iray reports a different value than GPU-Z does. :) You can also tell GPU-Z to log values over time so you don't have to sit there watching the UI through the course of your render.

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