Which computer advice?

[pjkw]

Just for reference / fun @1920x1080 i get 1m 2s with 32 MSR, 37s with 6 MSR.
I have a Ryzen 9 3950x (16 cores, 32 threads)

[dlparisi]

First off...a big thanks to Vipera, Alex, and pjkw (and anyone else that's contributing here). I really appreciate all of your efforts.

Adding to my continued confusion...if I turn off displacement and render with MSR 6 I get a blistering time of just 16 seconds. Irregardless of my previous times, this new time significantly improves on Vipera's time of 41 seconds on his 6950x. Where his time with displacement on only increases by about 60% (41 seconds to 65 seconds), mine increases by about 550% (16 seconds to 1m30s). This leads me to think there's something off in the way that memory/cpu is being handled for displacement on my system. Is this normal? Any ideas?

BTW-system has 64gb so it's not an issue of not enough ram during displacement.

[dlparisi]

Further, if I set the Env. Variable VRAY_NUM_THREADS to half on my system, 36, I get a time of 1m45s for 6 MSR. CPU utilization is just about half at 49-50% (vs ~100% normally) but the time only increased by about 15-16% (15 seconds). Weird. Is this possibly related to the high core count, NUMA nodes, multiprocessor? Anyone have any ideas?

[Alex_M]

As far as I know, the new Threadripper 3000 series CPUs (3960x, 3970x) are now single NUMA domain (as most ordinary CPUs) compared to 4 NUMA domains on the old 32-core Threadripper 2990wx which sometimes had issues in workloads which were not NUMA aware. So the new Threadrippers shouldn't have any NUMA related problems/slowdowns seen in the old 24 and 32 core 20000 series Threadrippers unless you manually change the NUMA configuration in BIOS.

[Vipera]

Guys, thank you for your tests! I am digging the problem. I believe that when I just assembled the system my render time on Threadripper was faster but something happened after few days. If I can find the problem I will let you know. Thank you for your help!
Update. It looks like I am having a problem exactly with that waterscape scene only. I have tried to render some other scenes and found out that Threadripper render time is smaller than my i7-6950X. I have no clue what wrong is with this scene. :-/ And that scene was the first scene I had to render on my new Threadripper 3960X.

[dlparisi]

I wonder if your troubles with the TR machine are in any way related to the odd displacement and thread behavior I mentioned? I tried a lot of things to get it to speed up on my machine: redoing the displacement as a modifier, rebuilding your water shader with a new VRayMtl, resetting VRay, etc and nothing really seemed to change the odd behavior.

[dlparisi]

Still fooling around with this and I did notice one thing that makes the displacement take a lot longer, the 3ds max "composite" map. I started by replacing the displacement map in the scene with a Composite map with just one noise map layer in place and it rendered in 58 seconds. I then replaced this Composite just with just the noise map and it rendered in just 29 seconds. Thinking that it might just be a result of the extra math going on in the Composite map I placed the noise map into a VrayCompTex and again got 29 seconds. I then went about recreating the Composite map from Vipera's scene into a VRayCompTex map which required a bit of values adjustment since the Composite map has a few more controls (mainly the opacity amount). I was not able to get it to align perfectly with the original (it looks to be a little lower) but other than that it seems to have the same displacement. In short though it rendered out in just 45s compared to 1m30s originally, half the time!.

Now what I don't know is, is this just a general slowdown meaning that the Composite map is just slower for some reason or is it specific to my system (and perhaps Viper's TR as well). I've attached a zip file with just the water that has the new texture map in place (just merge "Water" into the previous scene with the frigate). The material still has the old composite map in a disabled self-illumination slot to able to compare. Hopefully someone can try it out.

Water Only.zip

[Alex_M]

I rendered the scene with your water object and I get 33 seconds render time at 1920 x 1080px with my TR 3970x.

[squintnic]

interesting thread, was about to get another 3950x for general use and phoenix.
was worried after the horrible performance of my 2990wx...

[Paul Oblomov]

Well, you should update windows to the latest version to use updated perfomance profiles + new tr friendly scheduler. But, from my tests - 3960x had some weird issues with vray. But, still not 100% sure. Digging...

[dlparisi]

I rendered the scene with your water object and I get 33 seconds render time at 1920 x 1080px with my TR 3970x.

Thx. Was that at 32 or 6 MSR? You had about a minute for 32 so if this was for 32 as well it just speaks to a general slowdown of displacement with composite map.

[piotrus3333]

composite map was always slow no matter how you use it.

[Alex_M]

Thx. Was that at 32 or 6 MSR? You had about a minute for 32 so if this was for 32 as well it just speaks to a general slowdown of displacement with composite map.

That's with MSR of 32.

[Vipera]

Conratulate me guys, I have nailed the problem in render time slow down, and problem is not in V-Ray. Now I have to complain on another forum. I use FumeFX plugin in this scene with the ship. FumeFX plugin adds his FusionWorks renderer to Environment effects. So, if you don't have FumeFX or Afterburn plugins installed, your render tests do not calculate similar results as on my computers because I have FusionWorks render enabled in my shared test file.

Slow render happens because of FusionWorks Renderer from Afterworks (Afterburn and Fumefx plugins).
FusionWorks Renderer
ON
i7-6950X render time: 2m 51s
Ryzen 3960X render time: 5m 51s

OFF
i7-6950X render time: 1m 53s
Ryzen 3960X render time: 1m 11s

As you can see, FusionWorks Renderer slows down render on i7 as well but not so critical as on Ryzen computer. It is time to contact Afterworks company now.
Update: I wrote complain on Afterworks forum. I recently wrote on their forum that Afterburn has 32-core limit and crashes when it tries to use more cores. I thought that FumeFX doesn't have this problem but looks like there is a similar issue. Thank you for your help, guys!

[Alex_M]

Good to hear. Yes, I don't have this plug-in installed.