SU Podium Forum
Register  |   |   |  Calendar  |  Latest Topics
 
 
 


Reply
  Author   Comment   Page 2 of 2      Prev   1   2
max_rockatansky

Avatar / Picture

Registered:
Posts: 22
Reply with quote  #16 
Quote:
Originally Posted by JustinSlick
As for diminishing returns -- the beautiful thing about CUDA is that it scales almost perfectly.  I've seen benchmarks from Migenius that stated 96% scaling efficiency for Iray, which is pretty incredible.  So you really do almost double your performance by adding a second card... and on and on as you keep adding cores.

As for 1080 vs 11xx.... there are some pretty insane rumors about how powerful the 1180 will be. I don't think anything is confirmed yet, but I think I'd be hesitant to buy a 1080 right now, especially with the prices inflated.


What percentage of the GPU(s) is utilized during an Iray rendering? I recently installed two 1080 Ti's and got a license for Prowalker GPU. In a non SLI configuration one card is almost fully utilized and the other card is 1-5% utilized in the task manager performance window. Switching to a SLI configuration one card averages 60% utilization and 40% average for the other card. Sometimes both cards will total up a bit over 100% between the two but briefly and never any where near 200% total together. Just curios if this is what you have seen with a two card setup or if something in my configuration is causing a bottleneck. 

Timaphillips

Registered:
Posts: 71
Reply with quote  #17 
That's a lot of ooomph needed from the CPU. What CPU do you have, I would assume if you've got SLI 1080ti's you've got a current gen "K" Intel at minimum. 
max_rockatansky

Avatar / Picture

Registered:
Posts: 22
Reply with quote  #18 
I7-5820K 6 core/12 thread. It lights up to 100% In Prowalker GPU just like it does for Podium. 
JustinSlick

Avatar / Picture

Moderator
Registered:
Posts: 407
Reply with quote  #19 
I have noticed that too... we have a multiple 1080 machine here and in the Windows task manager it appeared two of the GPUs was nearly idle (around 5% like you said).

I downloaded the Techpowerup GPU Z resource monitor, and it seems to provide a more accurate depiction of what was happening.  It looks like GPU utilization on each card jumps around quickly from around 5 to 90ish, in pretty rapid sequence...  I'm thinking there must be a slight pause every time a new iteration finishes.

I don't really have the technical background to shed any light on this, but your actual GPU utilization might be higher than it seems in the Windows task manager.  

My intuition here is that Iray is scaling very well for us, but I sort of doubt we're getting the 96% scaling efficiency that Iray is capable of on a perfectly optimized machine.

Our cards are in an external Cubix Xpander box instead of in the main chassis.... I have no idea how that affects overall performance.  But GPUZ is definitely showing that all our cards are being utilized pretty equally.

__________________
What's New in SU Podium?
What's New in Podium Browser?
Timaphillips

Registered:
Posts: 71
Reply with quote  #20 
I recommend HWMonitor for watching system resources all at once. Windows build built-in resource manager is junk- doesn't even read CPU speeds correctly most of the time. 

SLI is notorious for nuances like this and outside of $$$ it's the reason I stay away. I'm tuned in here to see what the dev finds out just out of curiosity. Just like video games, I'm fairly certain the software needs to work in conjunction at the driver level (Nvidia in this case) to work at full efficiency in SLI or any GPU. 
JustinSlick

Avatar / Picture

Moderator
Registered:
Posts: 407
Reply with quote  #21 
Great tip, thanks!
__________________
What's New in SU Podium?
What's New in Podium Browser?
max_rockatansky

Avatar / Picture

Registered:
Posts: 22
Reply with quote  #22 
Justin and Tim, you were both right with Windows task manager being a terrible resource monitor. I took a quick look at CUP-Z and HWMonitor from CUPID but I ended up installing MSI's Afterburner overclocking utility. Along with being able to adjust any setting on your GPU it has pretty good resource monitor tools built in. I set it up to display 18 parameters out of the 60-70 that were available. You can adjust the polling interval in milliseconds and even record the monitor. A quick test of ProWalker GPU shows both cards being fully utilized. In the graph you can see the second card's utilization dips further than the first card's dips through the render process. This seems to match up with the performance increase of multiple GPU's in the NVIDIA Iray GPU Performance Comparison article here: https://www.pugetsystems.com/labs/articles/NVIDIA-Iray-GPU-Performance-Comparison-785/


I plan to tweak some of the GPU's settings to see if I can improve render performance and decrease power and heat on the cards. GPU2 sits between the CPU and GPU1 on the motherboard and runs noticeably hotter right now. I may add another fan in the case to see if I can get the two temperatures closer together.  

  

Attached Images
jpeg MSI Afterburner Graphs.jpg (152.76 KB, 4 views)

JustinSlick

Avatar / Picture

Moderator
Registered:
Posts: 407
Reply with quote  #23 
Quote:
SLI is notorious for nuances like this and outside of $$$ it's the reason I stay away. I'm tuned in here to see what the dev finds out just out of curiosity.


Yes, I asked about this and it doesn't sound like SLI is recommended for Iray. It may not hurt performance outright, but I don't think it helps.

Quote:
This seems to match up with the performance increase of multiple GPU's in the NVIDIA Iray GPU Performance Comparison article here: https://www.pugetsystems.com/labs/articles/NVIDIA-Iray-GPU-Performance-Comparison-785/


Nice article, thanks for the link. Great to see more info on how well it scales as you add cards.

__________________
What's New in SU Podium?
What's New in Podium Browser?
Timaphillips

Registered:
Posts: 71
Reply with quote  #24 
Quote:
Originally Posted by max_rockatansky
ended up installing MSI's Afterburner overclocking utility. 


Afterburner is a must have for GPU control, even if you don't overclock. I prefer Afterburner for GPU monitoring and GPU fan control. HWMonitor for everything else. Especially important to watch CPU temps when rendering. Then you can go into BIOS and tweak system fans as needed. 
max_rockatansky

Avatar / Picture

Registered:
Posts: 22
Reply with quote  #25 
Quote:
Originally Posted by JustinSlick


Yes, I asked about this and it doesn't sound like SLI is recommended for Iray. It may not hurt performance outright, but I don't think it helps.


From my bit of testing I got the same performance regardless if SLI was on or off with my two cards. I got different readings in Windows task manager but speeds per frame were the same. Since I have a bridge installed I'm just going to leave it in unless it starts to cause problems down the road. 
max_rockatansky

Avatar / Picture

Registered:
Posts: 22
Reply with quote  #26 
Quote:
Originally Posted by Timaphillips


Afterburner is a must have for GPU control, even if you don't overclock. I prefer Afterburner for GPU monitoring and GPU fan control. HWMonitor for everything else. Especially important to watch CPU temps when rendering. Then you can go into BIOS and tweak system fans as needed. 


Under monitoring settings in Afterburner you can graph usage, clock speed and temperature for each individual CPU core. Viewing that many graphs at once will take up a lot of real estate on you monitor though.
Previous Topic | Next Topic
Print
Reply

Quick Navigation:

Easily create a Forum Website with Website Toolbox.