Iray suddenly using 100% of my CPU

Mike B

What changed? One day my renders are useing 100% of my GPUs then the next day renders are useing 100% of my 8 core CPU and

And taking much longer to render WTF? 

Richard Haseltine

Same scene? Are you running different applications that might be taking enough extra RAM on the GPU to stop the scenes from fitting? Driver update?

Grin Smirk

I've notice a similar issue and was looking for an answer,

In my case one scene will use the GPUs in another it won't use anything but CPU (also an 8 core processor like OP),  Watching the history as it renders Iray does briefly access the card(s) loading geometry and textures,  GPU-Z shows memory on the cards in use, however aside from the 2 brief spikes in the beginning of the rendering the GPUs stay flatline at 0% and the CPU goes at 100%

I've attempted several different setups and current drivers, some examples:

2 Quadro 4000s

2 Quadro 4000s; 1 Quadro K620, 1 Quadro K420

2 Quadro 4000s, 1 Quadro K620, 1 GeForce 730

(note: same Mobo, CPU, RAM, HD configuration and clean driver installs between experiments)

Padone

when iray reverts to cpu it always reports errors in the log file, so you can look there for more info .. help > troubleshooting > log

Tobor

Dittor on the log thing.

Grin Smirk, some of the cards you list may either not have enough VRAM for anything but a very simple scene, or may not support the proper CUDA core compute level for Iray. This would be particularly true with any of the older Quadro cards. Some of these have so  few cores anyway, it's probably not even worth the bother trying to get them to work with Iray. The log will indicate either or both of these reasons for Iray failure. 2GB isn't very much for a scene -- just a character with some basic clothes and hair. A setting and/or second character might be too much.

Grin Smirk

Tobar & Padone, the info was very helpful.  The log messages where somewhat vague but with the suggestion about insufficient VRAM lead me to do some experimenting and a scene which had previously gave me issues was able to render with all GPUs after some heavy Decimation of characters and props, plus a subsequent reduction of texture sizes.  The resulting render was lack luster to say the least but confirmed the issue.  Four G3 models where producing 300+ Mb in geometry alone, lol.  So some of my more ambitious project will have to wait for new video cards.

The help was very appreciated.

Grin

Tobor

Just as a BTW, it's usually textures that take up the most space. G3 and non-HD figures are pretty conservative in their size, so they take up only a reasonable amount. Textures, on the other hand, can easily go past the 500M mark for one or two characters (more with lots of clothing). With only 2G to play it's easy to overfill VRAM.

Iray has a texture compression feature; it's found in the Render panel. The settings alter the thresholds of the compression. Though it takes longer, you have more control if you compress the textures yourself by making them smaller. Note that the file size of the texture doesn't matter, but the decompressed size. It basically comes down to width and height dimensions. If you''re not doing closeups, 2K for skin textures is often acceptable, and it's 25% of the original texture size in memory (ex: 1M to 250K).

Padone

Totally agreed with Tobor. Just a note on compression rates. The high rate tends to generate artifacts that are mostly visible in geometric figures such as straight lines, sharp borders etc. So it is better to set it for 2K textures and above rather than the default 1K textures.

Also I believe you may find these threads interesting

https://www.daz3d.com/forums/discussion/158961/11-gb-vram-insufficient-for-5-characters-for-iray-rendering

https://www.daz3d.com/forums/discussion/160336/grainy-lighting-is-there-a-way-to-remedy-this