Terragen and hyperthreading

Started by james adamson, March 06, 2020, 12:09:22 pm

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james adamson

Hi all.
I have a 10 core processor Intel xeon w 1250b which I believe gives me ten virtual cores.
I have overridden automatic core detection and put in 10 and my render time is identical to when it was set to automatic.
Does Terragen detect the physical cores and not the virtual ones meaning that 10 is all it will use?
Cheers.
James.

WAS

No. It uses virtual cores. For example my Ryzen 5 2600 is a six core, and registers to TG as 12 core.

james adamson

Weird. Halving the available amount in prefs made no difference to render times.

masonspappy

Quote from: james adamson on March 06, 2020, 02:25:49 pmWeird. Halving the available amount in prefs made no difference to render times.
Perhaps I am wrong, but I thought the idea of "available cores" was to restrict the # of cores that Terragen uses so that remaining cores could be devoted to other uses?

jaf

Quote from: masonspappy on March 07, 2020, 08:42:00 am
Quote from: james adamson on March 06, 2020, 02:25:49 pmWeird. Halving the available amount in prefs made no difference to render times.
Perhaps I am wrong, but I thought the idea of "available cores" was to restrict the # of cores that Terragen uses so that remaining cores could be devoted to other uses?

No, I believe you are correct.

There's a few things to be aware of.  In my case, I get 16 cores available if I don't override the core detection in preferences.  If I want to render at 50%, I set the maximum threads in the render advanced tab to 8.  However, sometimes I need to be careful with the heat, and while setting the max threads to 8 keeps the TG core usage to around 50% during the render, it does not throttle the populating phase when a render starts (so core usage can go to ~100%.)  I've had my computer shut down due to heat limits I've set -- not because of the actual rendering, but the population calculation.

So, overriding core detection to (in my case) 8, will limit TG usage to ~50%.  Of course, added to that will be whatever else your system is doing. 

 
(12Sep20) Ryzen 1800x, 970 EVO 1TB M.2 SSD, Corsair Vengeance 64GB DDR4 3200 Mem,  EVGA GeForce GTX 1080 Ti FTW3 Graphics 452.06 (17Aug20), Win 10 Pro x64, Terragen Pro 4.4.42 Frontier, BenchMark 0:10:02

james adamson

Hi guys.
Yep I reduced my available cores by 50% whilst doing other tasks then when I went to bed set it back to default. i.e 100% but the render times are the same.

D.A. Bentley

April 08, 2020, 01:23:33 pm #6 Last Edit: April 08, 2020, 01:38:12 pm by D.A. Bentley
Your CPU has 2 logical cores per physical, and since you have 10 physical cores if you leave Terragen at it's default Automatic Core Detection, it should register 20 cores.  If you set it to 10 cores you would only be using 50% of your CPU.
If you are only seeing 10 virtual/logical cores then maybe you have Hyperthreading turned off in the BIOS?

Also I think you might have meant you have a "Xeon W-2150B". 

Hope that helps!

Derek