8 cores - running at 38%?

[RTurner]

I am using an 3ghz 8-Core mac pro with Max 9 and VRay 1.5. I am using Irradiance mapping primary, light cache secondary. When it transforms the vertices it uses one core, when it calculates the prepasses it uses all 8 but only at an average of 38-48%. When it renders the image it goes to about 60% x8 cores. Is there any way to make it use all the cores potential for the passes? Low priority thread is off. Light cache passes set to 8. The scene is about 1.5 mil polygons.

 

Why cant VRay use 100% of the processor to calculate my prepasses and rendering all the time? Is this normal on other systems?

[Vince Paske]

Its strange that its 38%, not 25% or 50%.

 

Anyway, try this:

 

Open up Maxscript Listener (F11) and type in

 

renderers.current.system_numThreads=8

 

and in your Light cache dialogue, set number of passes to 8

 

Hope that helps

[RTurner]

Ive done that....could there be a bottleneck somewhere so that the "thread manager" cant send the threads fast enough?? This is a fairly complex grocery store scene. There are approximatly 400 materials in the scene using about 345 jpgs that total 21megs. All of these are stored and pathed to my hard drive. I'll test something a little less complex at lunch and see what i can learn.....brb.

[RTurner]

I did a simple scene (1000 glossy white teapots with high GI) and got 100% usage across the board.

 

So it is possible for me to utilize 100% performance, but I have created a scene that prohibits this from happening. Can I do anything to my scene to get all 8 cores humming along at 100%? Setting a material override using plain white did nothing for me....

 

Below are the stats for my scene....

[Matt McDonald]

Different parts of the rendering process generate different processor loads. Just because you have 8 cores doesn't mean that Max is going to nail them all at 100% all the time. It does sound like the system is scaling so IMHO watching task manager is just going to give you gray hairs.

[RTurner]

Im not concerned with it being tapped ALL the time just the 29hrs it take to render my scene! Do larger scenes generally use less of the processors performance?

[BrianKitts]

Different parts of the rendering process generate different processor loads. Just because you have 8 cores doesn't mean that Max is going to nail them all at 100% all the time. It does sound like the system is scaling so IMHO watching task manager is just going to give you gray hairs.

 

That's true you will see some fluctuation between loading maps, completeing prepasses, etc.... but when you hit the point of actually rendering.... your processors should be pinned on 100%, speacially for a large scene.

 

Im not concerned with it being tapped ALL the time just the 29hrs it take to render my scene! Do larger scenes generally use less of the processors performance?

 

 

My current project has about 200 vegetation proxies on a large terrained site, with a couple of high poly cars.... I would consider it to be a large scene when it renders it hits 100% the entire time, what you are experiencing isn't right.

[RTurner]

Any theories on why this is happening? I have my own, but I am interested in what the rest of you think...has anyone else experienced this performance lag? or am I on my own?

[Matt McDonald]

Im not concerned with it being tapped ALL the time just the 29hrs it take to render my scene!

 

I would agree that if we are talking about 29 hrs there is a problem.

 

From the looks of your task manager screen grab, you don't have a ton of available RAM while rendering (300mb if I am reading right) this could be your bottleneck.

[RTurner]

Why would unused Ram create a bottleneck? This is another resource that windows could use if needed. Are you saying that if I had an extra gig of unused Ram this would cause the processors the work full speed?

[Matt McDonald]

I'm suggesting that your RAM is bottoming out. Once that happens the CPUs are going to be waiting on data to process.

[RTurner]

That makes sense, what is the best way to determine actual memory used? I ordered the system with 4gigs of Ram but the task manager only shows 2gigs, I have used a 3gig switch. but I cant tell if its working. Will XP show more than 2gigs installed? I really hate Windows in this regard.......

[Matt McDonald]

XP 32 bit will show about 3.2gb of RAM in task manager (even if you have 4Gb installed). The 3Gb switch will let any one application use up to 3Gb of physical memory as opposed to the 2Gb limit imposed without the switch.

 

As to why your machine is only showing 2Gb total in task manager, I'll have to defer to someone with experience running Windows on a Mac.

 

Are you using Bootcamp? There are a handful folks around here that do, so that one should be pretty easy to troubleshoot.

[BrianKitts]

you may want to try a post on chaos' forums in the problems section.... Vlado is normally pretty good about attacking problems like this. Only problem being he will probably ask you for the file to test.... which if you aren't allowed to do he might at least be able to give some insight....

 

http://www.chaosgroup.com/forum/phpBB2/viewforum.php?f=3&sid=18b3ec44caf7adc9b7213c9b24881829