Cloud Layer reduces number of cores in rendering ?

Started by boitaclou, October 19, 2016, 07:27:55 am

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boitaclou

October 19, 2016, 07:27:55 am Last Edit: October 19, 2016, 07:30:45 am by boitaclou
Hi all,

I'm new to Terragen (TG4) and i noticed a strange behavior with Clouds Layers. Maybe it's just a setting problem (i'm discovering TG), but i would like to share it... I didn't found similar problem in the forum, so here it is :

I'm on a Mac Pro 2012, 12 core 3.33 Ghz. When i render a scene in the render view (not a particular scene : the startup scene works fine for exemple), all 12 cores are used ("Override automatic number of cores detection" is unchecked into préferences). But if i add one of following Cloud Layer :

- High Level Cirrocumulus,
- Any of Mid Level Clouds,
- Any of Low Level Clouds,

only 6 cores are used when rendering (divided by 2)... If i add "High Level Cirrus (2D)" or any of Global layer, the 12 cores are used.

I think i missed some optimisation setting, but i don't know where...

I tried to play with "Acceleration cache" in the Optimisation tab of the Cloud Layers, with the number of threads in the Render node Advanced tab, but they had no effect on the number of cores.

Here is a screenshot with the startup scene and a mid level Cloud layer added.
This is not a blocking issue, but if my 12 cores could be back...  ;D

BR.

ajcgi

In the brief time I've been able to play about with TG4 on the Mac recently I had the same issue.
No idea what I've set up wrongly. Been using TG for years.

Matt

The presets that you reported are not fully utilizing your cores are using the new Easy Cloud or Cloud Layer V3 nodes. Both of these are new to TG4 and make heavy use of voxel buffers. There might be some bottlenecks in our implementation that are reducing parallel performance, and on the Mac this might be reported as using not all cores or hyperthreads (but I am speculating here).

This is something I'll try to improve.

I notice this screenshot was taken quite early in the pre-pass. If you let the render continue to the end, does CPU utilization increase later on?

Matt
Just because milk is white doesn't mean that clouds are made of milk.

boitaclou

Hi ajcgi, Matt,

Thanks for reply.

No, CPU utilization doesn't increase until end. I could even say "it decreases" because utilization decreases to about 40% of the 6 cores as soon as the terrain seems to be rendered.

Here is a screenshot of the utilization history. After 5 mns rendering, utilization is the same as the last image until end.

Hope this helps.

BR

Oshyan

This issue appears to be much worse on the Mac. We are looking into it.

- Oshyan


Oshyan

We've found at least one major bottleneck which we should be able to address soon and will help a lot. We'll release an update as soon as we can. Thanks for your patience.

- Oshyan

boitaclou

I've just tried version 4.0.04 : works fine !
Thanks for update  :)

BR

Oshyan