VRAY: Low CPU and High RAM(Memory) Usage!

[videep]

Hello Everyone,

 

I recently came across a situation while using VRAY 1.5. When rendering files sized 1gb+ on machine:

Ram:12gb,

CPU - i7, 322ghz

 

It slows down like anything. 10 hours to reach 1/4th of prepass 3 of 3.

Observation:

High Disk I/O, reading and writing 3ds max temp files,

Low CPU Usage(only 1-10%),

High Memory(95%)

 

This makes the render times go upto 10h where as on render servers with 32gb ram and 16core CPU, it renders in 1h.

Looking at the computer specifications, A guess of rendering time on server vs machine would be a straight double. But this is 10 times high!

 

What would possibly be the reason for such slow down?

 

Thanks in advance.

[numerobis]

If you're running out of RAM the system starts using the pagefile. This is MUCH slower than using the RAM because a HDD or even a SSD is much slower than the system RAM: DDR3 1600MHz in quad channel has a bandwith of ~35000 MB/s, a SSD maybe a transfer rate of ~500MB/s and the best HDDs maybe a up to 150MB/s average transfer speed. And the access time is even more different: DDR3 RAM has a few nanoseconds, a good SSD around 0.04ms = 40000ns and a HDD maybe 15ms = 15000000 ns !

And besides the rough values the other point is that everything on the HDD/SSD must be loaded into the RAM to be accessible and written back after the operation to free space for the next one... so the whole process is much, much slower than direct access.

Edited March 23, 2014 by numerobis

[Jason Matthews]

Go to the system tab and change the memory usage from static to dynamic and type like 10GB instead of the 512 that they have defaulted. Sorry I have not looked in the tab in a while and forget what it is all called.