Slaves with 8 CPU cores rendering slower than slaves with 4 CPU cores

V-Ray V-Ray for 3ds Max Issues
1

We have a mixture of render slaves, 4 of them have 4 CPU cores and 4 of them have 8 CPU cores. They all have 4GB ram.

Ordinarily, the 8 core machines are significantly faster than the 4 core machines, close to twice as fast. We are running through an animation at the moment, and for some reason, the 8 core machines are running about 25% slower than the 4 cores. I have obviously changed something that has affected things somewhat.

I have changed the face/level coefficient to 2.0 and changed the dynamic ram to 2000MB. The scenes are reaonably complex with quite a few proxies, textures and wind-animated trees (which are not part of the pre-calced GI solution). Memory useage whilst rendering is around 3GB.

Would either of these two settings slow down the renders from the faster machines?

2

my comment isnt an answer to your problem but something that was brought to my attention recently from Boxx Tech…I have Xeon 2.26 16 core workstation and recently i was asked in the bios to change this

Please ask Lee to check this bios setting due to some newly discovered changes.
Advanced – Processor & Clock Options – Simultaneous Multi-Threading – Disable

For some reason im told and maybe corrected that some people disable this and means rather than me getting 16 buckets for the 16 cores while rendering i get 8,which i think im told is more powerful,how much i dont know.

Maybe someone could expand on this if suitable to the topic

Hope u get it sorted

3

Nope. Did you try disabling the bitmap pager?

Best regards,
Vlado

4

Is memory usage the same (3GB) on both 4 and 8 core machines?
My experience is that machines with more cores reach the dynamic memory limit far sooner then machines with less cores: try setting the limit on the 8-core at 3GB.

5

No. Funnily enough, the bitmap pager is the other item that I changed over the face/level coef and the dynamic RAM. I’ve never really used the bitmap pager, but due to the amount of memory my scene has been using whilst rendering (up to 7GB), I enabled the Bitmap Pager. I also enabled it on all the render slaves. How would this affect things, and what should I do to improve it? I worry that disabling the bitmap pager may mean that my render slaves fail to render because they don’t have enough memory.

6

I believe it is the same. How would I enable a different limit on some of the machines and not others? I though this variable was set by the scene that is sent to backburner.

7

You’ll need to split your scene and sent jobs with different limits to the different nodes (4GB and 8GB mem) :wink:

8

Although that may be a temp solution, it all sounds a bit backwards to me, and there must be another solution

9

This is the 3rd time I have written this - I keep pressing ‘reply’ instead of ‘post quick reply’! It drives me mad.

Anyway, in order to get my slaves to have bitmap pager enabled, I copied the max.ini file from my local quad-core workstation to each of the slaves, both 4-core and 8-core. Is there something in the ini file which tells max the machine only has so many cores???

10

At one point there was a Maxscript command to set the number of CPUs to render with. This would get baked into the file. I don’t remember why people were doing this, but the following command would basically reset that to use all available CPU/cores.

Just type the following into the maxscript window and hit enter. It’s a long shot, but who knows!

renderers.current.system_numThreads=0