CPU low load on rendering

[sirr]

Hi,

 

I have Opteron platform with two dualcore CPU-s and i use Viz 2007.

While rendering with V-Ray or computing the radiosity the load of 4 CPU-s is 100%

While rendering with scanline renderer, CPU-s load does not exceed 27%.

Can someone comment this weird situation? Where is the bottleneck?

 

Regards,

gert

[Matt McDonald]

When speaking of the scanline renderer, the entire process is not multi-threaded and never has been. The process of "preparing lights" will only run on a single core. The process of rendering (when Max is actually creating the image) is multi-threaded and will scale across all cores.

 

If this is not happening you might not have multi-threading enabled. Go to:

customize - preferences - rendering tab and make sure that "Mulit-threading" is check on.

[sirr]

nope, all necessary options are selected. Remember - while rendering Vray or computing radiosity, the load is fully 100%. Only scanline render behaviour is weird.

[Matt McDonald]

again, using the scanline render the entire process is not multi-threaded so it will not use all cores all the time.

[sirr]

I see. But in my case it uses all cores all the time(according to task manager performance tab) and all of them 25-30 %. It means there are no differences in preparing lights or rendering. All the same!

[Jefferson Grigsby]

I would be willing to bet you have some architectural materials in your scene, the viz 2007 tipped me off to this. They are complete crap and will bog Vray down. They appeared a few years ago in the "Viz-render" crap engine that Autodesk peddled onto unsuspecting architects as a solution to directly epxort model from AD to viz, promising photorealistic renders at the mere push of a button. They should be avoided by anyone sober who prefers to finish jobs on time.

 

Bottom line is that they use Viz's raytrace engine for relflection, which drives Vray bonkers. Just don't use them. Make sure all of the materials in your scene use Vray materails and you will be fine. There are sime nice plugins that will batch convert for you.

 

Hope this helps

[sirr]

Thank you for the answer, Jeff.

 

My problem is not in Vray. I'm using standard materials and scanline render. I certainly do not use architectural materials.

 

Take a look please at the picture attatched to this post.

[Matt McDonald]

I think that you need to trust that the Max scanline render is taking advantage of your hardware as best it can. There are no more settings in max to change. Based on the image that you have posted at one point max does indeed max out your CPUs but then backs off.

 

There are other peculiarities about how max uses system resources that will drive you crazy if you spend too much time looking at task manager. For example: max will use a significant amount of virtual memory even though there is still physical memory available.

 

I'd take comfort in the fact that you have very nice hardware and your software is set up correctly.

[sirr]

I discovered that increasing "Rays per sample" value at "Regather Indirect Illuminaton" from 25 to 60, the CPU-s load grows from ~30 to ~75%.

How can those values be connected with CPU load? Why is'nt the load 100% like in V-ray rendering?

 

About virtual memory - I bet it's our friend Windows who manages VM so cooly!