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View Full Version : LW not using CPUs when rendering, why???



SNOOPY33
04-13-2010, 08:32 AM
Hello, I'm running LW 64b in Windows 7
I made a scene and render fine, but I bought a brand new computer,
exactly the same specs, an i7 to be dedicated just to rendering.
I load the scene without any problems, but
when I set it to render it shows that it will take many many hours.
When I check CPU usage in the Task manager,
none of the CPU's is being used.
at the most I get 5% overall.

I called Newtek but the tech support guy had no idea.

Anybody had this problem before?

Thanks in advance!!!
Snoopy
:help:

Tobian
04-13-2010, 09:22 AM
Ok
1) what camera are you using? If it's classic camera, it's use of multiple cores is not always optimal.

2) in your render globals, what is your 'multithreading' set too? If it's set to auto it should distribute the work between cores, but maybe set it manually to the number of cores (or in the case of an i7 the number of virtual cores) you currently have, just to make sure LW is using it optimally.

3) What specifically are you trying to render? have you just opened up a blank square with something simple like a cube or circle in it, you created from scratch in that version of LW. If it's fine, then it may be something odd with your scene file? Sometimes if a scene file has been created in an older version of LW and you open it in a newer version, it can be corrupted slightly, so create blank scene, and then 'load items from scene' and load everything in, and save it out again. It could just be you are doing something really weird with your scene, which is bogging down LW, like you're trying to render 7 billion polygons, a volumetric hypervoxel or a tonne of hair!

SNOOPY33
04-13-2010, 09:32 AM
Hello,
I'm using Perspective Camera

I've tried Multithreading Automatic, 8 threads and 4 threads,
still the same result.
The scene contains a lot of cubes with image mapping.
About 8,000 cubes.
But in one of the computers the scene uses 100% of the CPU.

Thanks in advance for any ideas.

Lightwolf
04-13-2010, 09:43 AM
Thanks in advance for any ideas.
How much memory do you have any how much memory is LW using?

Cheers,
Mike

SNOOPY33
04-13-2010, 09:46 AM
I have 8GB of Ram and about 93% is being used.

Lightwolf
04-13-2010, 09:54 AM
I have 8GB of Ram and about 93% is being used.
Hm, I'd suppose your HD Led is constantly on as well? I've got a hunch that you're basically just running out of memory.

Cheers,
Mike

Sensei
04-13-2010, 09:57 AM
I have 8GB of Ram and about 93% is being used.

This means that virtual memory is used and computer is constantly waiting for hard disk to deliver data..
In Task Manager, View, Show Columns you can specify showing real process virtual memory usage.

SNOOPY33
04-13-2010, 09:58 AM
Yes it's possible that I'm running out of RAM,
but why would the rendering work but at an extremely slow speed???
and why wouldn't use the CPU's?
The CPU usage is between 0% and 1%

Why???????????????????

Snoopy

Sensei
04-13-2010, 10:03 AM
Modern motherboards and processors are using interrupts. Instead of constantly checking by cpu, like in very old times, whether hardware is working/idle, there is send interrupt from hardware to wake up cpu and do stuff corresponding to interrupt. Application is basically waiting for hard disk interrupt and doing other stuff in background, like handling mouse and keyboard events (which are also send as interrupts), updating screen etc.

SNOOPY33
04-13-2010, 10:04 AM
So you think if I had some more RAM the CPU's processing would go up?

Lightwolf
04-13-2010, 10:06 AM
So you think if I had some more RAM the CPU's processing would go up?
Yup...

Edit: Well, either that or you optimize your scene to use less RAM - from what you posted I'd assume it's the images.

Cheers,
Mike

cagey5
04-13-2010, 10:09 AM
Couldn't you test the hypothesis by trying a simplified scene either smaller/no image maps or fewer boxes? If the CPU usage increases it shows what additional memory could provide.

SNOOPY33
04-13-2010, 10:17 AM
I'm trying to render the scene in a computer with 12GB of RAM and see if it goes considerable faster.

I'll post the result in a few minutes.

SNOOPY33
04-13-2010, 10:54 AM
This is an important discovery (for me at least !)
Even with the 12GB of RAM computer, the frame was taking about 16minutes.
So I decided to render the top 50% of the frame using "Limited Region".
It took about 45 seconds.