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Iray render settings and Optix

gibrril_fa945a6ceegibrril_fa945a6cee Posts: 550
edited May 2017 in The Commons

Hi all,

While rendering this weekend I noticed a significant drop in speed this weekend. Checking the task manager showed me that Iray had switched to the CPU for rendering eventhough it's the same scene, only shot through a different camera that renderered on the GPU previously. So I unchecked the CPU in my hardware settings to "force" Iray to use the GPU (a dual Nvidia GTX Titan of 12GB, SLI turned off). Also I unchecked the CPU in the Optix Acceleration settings. Now Iray renders on the GPU again, but still at a much slower pace than it did before when the CPU was still turned on in both the harware and the optix settings. I'm using Daz Studio 4.9 and batch rendering (to save time while I'm away. I have quality turned off, a max samples setting of 2500 samples. Before this switching to CPU happened I could squeeze 23 renders at a 4000 x 3750 resolution in a period of 15 hours and 30 minutes. Now I can "only" render 17 renders in a period of 17 hours and 30 minutes... What could be causing this? As mentioned I have two GPU's of 12 GB each, so what could be causing Iray to switch back to CPU? Is there a way to flush the GPU ram back to an empty state in between to renders of a Batch process? I noticed the first CPU render while doing a test render on it's own, not as part of a batch... Also the slower rendering seems to be "permanent": I turn my PC of at night, but this is the second day I've been having these slower renders. I turn the PC on, open DAZ Studio and start up the batch render process, so there could be nothing jamming up the GPU RAM I would think. Two GPU's of 12 GB are quite costly so I'd like to get the most optimal usage out of them. Also I noticed that when the CPU was still checked in hardware and in Optix, upon checking the progress of the renderings, my cursor moved in intervals and with a lot of delay as if my pc was streched to its limit. When rendering now, with the CPU uncchecked, my mouse runs smoothly. Could it be that when the CPU was still checked, Iray uses both togther? I never cchecked the CPU usage when rendering was stil fine, but now the CPU (ten core i7) is only used for 18% during render time. If I turn the CPU back on in hardware, is there anothe way to guarantee Iray will use my GPU?

Does it help or could it help to switch the CPU back on in OptiX eventhough I leave it off in hardware?

Thanks a lot,

Me

Post edited by gibrril_fa945a6cee on

Comments

  • Richard HaseltineRichard Haseltine Posts: 108,138

    OptiX is a single toggle, or at least I don't see a way to selectively toggle it for only some devices. It dose accelerate renders (sometimes), but it may increase RAM usage. Changing your camera angle could increase RAM usage if it brings new combinations of elements that (for example) increase the length of a typical path. You can get an idea of the resoruces used by consulting the log file (Help>Troubleshooting>View Log).

  • Oso3DOso3D Posts: 15,085

    I've found optix more trouble than it's worth. SOMETIMES it helps, often it makes things worse, and, personally, I don't really feel like doing a slew of test renders to find out.

     

  • gibrril_fa945a6ceegibrril_fa945a6cee Posts: 550
    edited May 2017

    Hm,

    I can see my CPU and both GPU's both in the hardware field and in the Optix Acceleration field... (render settings > advanced tab)

    Post edited by gibrril_fa945a6cee on
  • gibrril_fa945a6ceegibrril_fa945a6cee Posts: 550

    Also, what bothers me, is that it has been slower like this on all renders since Tuesday. Not just on some, but on all of them.

  • gibrril_fa945a6ceegibrril_fa945a6cee Posts: 550

    Never mind, I sloved the issue. Good old user error... Somehow I mixed up max samples and max time upon saving the next scene and swapped both values...

  • nDelphinDelphi Posts: 1,921
    edited May 2017

    OptiX Prime Acceleration has been great to me. I don't render without it. In my experience renders are slower without it and I have a GTX 960 and a GTX 1080.

    Post edited by nDelphi on
  • SlipmeisterSlipmeister Posts: 21
    gibrril_fa945a6cee said:

    Hm,

    I can see my CPU and both GPU's both in the hardware field and in the Optix Acceleration field... (render settings > advanced tab)

    When you enter the Advanced Tab you have two sections - Photoreal (outlined in red) and Interactive (outlined in yellow), the OptiX Prime Acceleration is connected to the Photoreal Section. The CPU and GPU options below that are for Interactive renders.

     

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  • ZilvergrafixZilvergrafix Posts: 1,385

    in My PC, Optix crash DazStudio when render in viewport, dunno the issue but it does not accelerate the way i want and simply turn off.

    maybe is my combo of hardware or GTX1060 6Gb is damaged.

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