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4.15 using 25% of CPU while rendering on GPU, slowing computer...

Leonides02Leonides02 Posts: 1,379
edited February 2021 in The Commons

Hello Everyone,

Lately, when I've started rendering I've noticed a slowdown in my other PC operations. When I checked my task manager, the Daz is utilizing about 25% of my CPU. This is only during rendering. While Daz is otherwise open, it utilizes less than 1% of the CPU. 

My hardware has "GPU" only checked and I'm not allowing CPU fallback.

I don't remember this behavior in 4.12, which was the previous version I had before upgrading. I used to be able to render and then do things in Photoshop, etc. Now, however, my mouse becomes stuttery and there's definite lag on my machine. 

Am I imagining things?

Post edited by Leonides02 on

Comments

  • Richard HaseltineRichard Haseltine Posts: 102,749

    Iray has always required a CPU thread for managing the render, that's why it's often a bad idea to try using both GPU and CPU.

  • Leonides02Leonides02 Posts: 1,379

    Richard Haseltine said:

    Iray has always required a CPU thread for managing the render, that's why it's often a bad idea to try using both GPU and CPU.

    Iteresting. Thanks, Richard. I've never noticed this behavior before, so I thought that was the issue. 

    Hm.

  • Leonides02Leonides02 Posts: 1,379

    BTW, I solved this by taking 2 threads away from Daz using my Task Manager. 

  • SevrinSevrin Posts: 6,310

    If you have Photoshop set up to use your GPU to render, then that could cause a slowdown.

  • Leonides02Leonides02 Posts: 1,379

    Sevrin said:

    If you have Photoshop set up to use your GPU to render, then that could cause a slowdown.

    I do, yes. But this hasn't been an issue before. 

    Ah, well. 

  • richardandtracyrichardandtracy Posts: 5,929
    It's normal on my older machine (8 thread, 4 core) for renders to take 25% CPU, it's fairly steady. IIRC I had a chance to try it out on a 6 core/12 thread machine for a trial run, and with the higher spec processor it stabilised at about 18% on that machine. Limited by how much data the GPU could handle I assumed and how fast the CPU could deliver.
  • kyoto kidkyoto kid Posts: 41,249

    ...when I'm working and rendering in Daz,I have nothing else open. I even set my AV to silent mode as I'm no online (I don't use Connect or Daz Central). The other matter is there are system utilities that need to keep funning which take up both CPU and memory resources.

    So I did a little experiment:

    Without anything else (but Task Manager and GPUZ) open CPU usage is down to 0% and memory usage about 9% (out of 24GB) With Daz open and idle that doesn't change CPU load. There was a momentary "spike" on three of the threads when opening the programme as indicated  the performance tab. Loading a scene (2 G3 figures with HDRI) caused the CPU load to again momentarily increase to around 50% but once the scene finished loading, it dropped to 0% (not bothering with memory consumption as both the Daz programme and scene take up system memory) . However during the render process, CPU load varies form 25% ot around 53% and all threads are active even though I am rendering on the GPU (12 GB available). CPU is not checked in the Render settings.  During the render process, GPUZ indicated that about 2.8 GB of VRAM was in use (the scene itself taking a little less as the displays with Daz and the render window open takes up a small amount of VRAM).

    So not sure why all the threads of the CPU remained active after the scene loaded to the GPU's VRAM..

    Running the 4.12.0.47 Beta on Windows 7 Pro, GPU:  Maxwell Titan-X,. CPU: Xeon 6 core/12 thread X5660 (Westmere). Memory 24 GB GSKill Ripjaws DDR3 1333 6 x 4GB in tri channel mode.

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