4.4.71 major render times issue?

[pixelsmack]

I apologize if I've missed an announcement or "known issue." I stepped away from Terragen for a couple months as I didn't have a need. I fired it back up and say there was an update. I went ahead and did it. Everything seems fine. At least until I started rendering. Crop region renders completed in a normal expected time. I even did my normal full "final settings" renders but at much lower resolution to check for any issues. Everything is fine. It's not until I initiated my final renders, in this case an easy 1280x720, AA3. It has some light scattered clouds at 2500 feet over water. I've done shots like this many times. They take anywhere from an hour to maybe an hour and a half at worst on my machine. My machine is a new 3960x AMD 24c/48t cpu.

My render wrangler reported that after 13-hours per frame he was killing my job. 13 hours?? I loaded my shot in disbelief. Nothing should be taking this long. Re-ran all my crop tests and smaller resolution tests and everything seemed fine. I even experimented heavily with different bucket sizes just in case. No real major difference. Then I fire off a full resolution 1280x720 frame and went to bed. I fully expected it to be done in an hour or so. I awake this morning and it's been rendering for 8 hours and still not done! I've attached the image in progress so you can see for yourself. It's nothing special.What is going on? I can attached the scene too, if anyone wants to investigate.

In this image below, my CROP REGION test patch is done in the lower mid right of frame. Where there are clouds. Relative to the image size I set the crop as a 2" by 2" square and rendered. That took 3-minutes. Quite normal. Yet when I do a full frame render, areas much smaller are taking much, much, longer.

[WAS]

Are you using the path tracer or standard renderer?

I have been noticing renders taking much longer than they should as well (past several versions), but this is with the path tracer. For example, similar to you a scene which previews at AA3 at same resolution of final will take 1 1/2 hours compared to the final at AA7 taking up to 16 hours. And I used to go to bed doing PT renders and waking up to them finished on my last machine, which was only a quad core. This one is a Ryzen 5 2600 6c/12t.

My server which is a dual CPU system, total 24c gets absolutely abysmal performance with Terragen on Linux. Takes literally days. So sad. htop always shows only one CPU really active too. I've tried forcing threads but no go. When I got it, even with only 1 CPU going, it was comparable to my Ryzen 2600 (which is still slow despite slower clock, there are still more threads and cores than my PC). Now not even close.

[Matt]

I'd like to try the scene file and see what happens here. How many threads are you rendering with?

[Matt]

A small bucket size can really slow things down, especially if there's a lot of ray tracing or path tracing. I never go smaller than 48x48. At higher resolutions I would stay above 64x64. The defaults are semi-adaptive to the number of threads anyway.

[WAS]

I've never had to edit the buckets, at least I have never tried but now I'm wondering if that could help on my server with similar issues. I tried doing those directions on forcing threads to use all core but still get an idle CPU I don't understand. It is a Xeon server setup and I know they are quirky. My x5450 had a few missing execution sets that blocked not only win10 but some software.

[D.A. Bentley (SuddenPlanet)]

A small bucket size can really slow things down, especially if there's a lot of ray tracing or path tracing. I never go smaller than 48x48. At higher resolutions I would stay above 64x64. The defaults are semi-adaptive to the number of threads anyway.

What bucket size would you recommend if I am rendering at 16,000 x 8,000 pixels?  Also 32,000 x 16,000?

[Matt]

What bucket size would you recommend if I am rendering at 16,000 x 8,000 pixels?  Also 32,000 x 16,000?

At these high resolutions the default settings should be fine, i.e. a Max bucket size of 256x256 with auto reduction enabled. At 4k and below you might benefit from using a smaller max bucket size, but it's difficult to generalize about.

[WAS]

At 4k and below you might benefit from using a smaller max bucket size, but it's difficult to generalize about.

That makes sense to a point, though I theorize the "heavy" areas of a render may eat up all the buckets, allowing none to continue forward, which may actually exaggerate the render times.