interesting difference between P3D and MSFS

[FBW737 511]

I noticed that the main thread in Prepar3D runs on core0 and the main thread is MSFS in my case runs on core9.

Which is better? I say core9 is better. Reason being is that core9 is the coolest core in the stack because its at the

top and therefore has better cooling because its nearest to the CPU cooler. Whereas Core0 has the worst cooling

because it is the at the bottom of the stack and therefore furthest away from the CPU. In my OCCT tests core0

on my i9 10900k can reach temps 20c hotter than core9. Why doesn't LM change the code so that the main thread

runs on the CPU nearest to the cooler?

[shivers9 1,174]

I don't recall ever having that much of a temp difference in cores when over clocking. May be normal but I wonder if it is caused by your cooling solution or maybe how your thermal paste is applied. Interesting question for sure! Maybe the guys with a clue will roll in with an answer.

Edited January 28, 2022 by shivers9

[FBW737 511]

Nay, It's not my cooling solution. I have a very well seated direct to die water block and liquid metal TIM. Hottest core max is typically 86c (core0) and coolest is typically about 70c (core9) after 1 hour of OCCT linpac with AVX. I don't bring it up because I have a cooling problem but because it seems to make sense that the core that is at 100% nearly all the time should be the one closest to cooler. I wonder if an affinity mask could make it so.

[F737MAX 5,493]

8 minutes ago, FBW737 said:

I wonder if an affinity mask could make it so.

Hmm... Affinity Mask, you say...? 🤔

https://www.avsim.com/forums/topic/612746-new-p3d-53-affinity-mask-calculator/?do=findComment&comment=4713056

Give it a try. It isn't required to run P3D on Core 0 any more.

 

Edited January 28, 2022 by F737NG

[IanHarrison 521]

6 hours ago, F737NG said:

Hmm... Affinity Mask, you say...? 🤔

https://www.avsim.com/forums/topic/612746-new-p3d-53-affinity-mask-calculator/?do=findComment&comment=4713056

Give it a try. It isn't required to run P3D on Core 0 any more.

 

Maybe a silly question but how do you know or measure that sort of thing? (Core position) I know how to see temps of different cores but position?

[neilhewitt 493]

9 hours ago, FBW737 said:

I noticed that the main thread in Prepar3D runs on core0 and the main thread is MSFS in my case runs on core9.

Which is better? I say core9 is better. Reason being is that core9 is the coolest core in the stack because its at the

top and therefore has better cooling because its nearest to the CPU cooler. Whereas Core0 has the worst cooling

because it is the at the bottom of the stack and therefore furthest away from the CPU. In my OCCT tests core0

on my i9 10900k can reach temps 20c hotter than core9. Why doesn't LM change the code so that the main thread

runs on the CPU nearest to the cooler?

CPU cores are not 'stacked' vertically on the die. They are laid out side-by-side - this is part of the reason the package for high core-count chips like Threadripper is so much bigger. Intel did experiment with stacked dies under a programme called Foveros but even then the CPU cores were together on a single die, and the only product that used it AFAIK (Lakefield) has been discontinued. AMD uses 'chiplets' - separate sub-dies in a single package - but these are also laid out side by side.

Every core is as close to the IHS as any other. Thermal performance is affected by many factors, but core placement on the die really isn't one of them. Also, thermal performance doesn't really impact actual compute performance unless the core is hot enough to throttle, and if it is then you need better cooling, not a different thread schedule.

Intel 12th gen chips introduced the 'Big Little' architecture with P- and E-cores and *that* definitely affects compute performance, so you'd care that threads were being correctly scheduled onto the right kind of core. Not having one of these CPUs to hand I can't see if LM has tweaked 5.3 in any way for this, but then neither do I know if MS has tweaked MSFS. Perhaps someone with a 12th gen CPU could chip in here?

[simbol 5,767]

A Core is a Core.. doesn't matter what number, all cores are designed to be as powerful as the others.

The point in affinity mask is to spread multiple applications on different cores, so not everything runs on the same core.. now I could argue, MSFS running on Core X + 1 instead of Core 0 can be and advantage, because by default many apps runs very shortly on CORE 0.. so by forcing an application to run on something different than zero.. you ensure it has more resources.

You can do the same thing to P3D thought via affinity mask, this way you ensure it runs on another core instead of zero.

Personally I don't bother with these cores and AF, etc. having the right settings (not everything to the right / maximum) inside your simulator is more important, and of course a good video card with plenty of memory.. DX12 will always need plenty of VRAM not matter what.

Best,

Simbol

[Christopher Low 5,324]

Isn't 86C a rather high temperature for the CPU?

[psolk 3,037]

1 hour ago, simbol said:

A Core is a Core.. doesn't matter what number, all cores are designed to be as powerful as the others.

The point in affinity mask is to spread multiple applications on different cores, so not everything runs on the same core.. now I could argue, MSFS running on Core X + 1 instead of Core 0 can be and advantage, because by default many apps runs very shortly on CORE 0.. so by forcing an application to run on something different than zero.. you ensure it has more resources.

You can do the same thing to P3D thought via affinity mask, this way you ensure it runs on another core instead of zero.

Personally I don't bother with these cores and AF, etc. having the right settings (not everything to the right / maximum) inside your simulator is more important, and of course a good video card with plenty of memory.. DX12 will always need plenty of VRAM not matter what.

Best,

Simbol

Until Alder Lake that was...  Now with -P cores and -E cores not all cores run at the same level.  So if core 9 is a -E core on Alder Lake you would be running at 3.6 instead of 5.1   

 

[flycln 435]

1 hour ago, Christopher Low said:

Isn't 86C a rather high temperature for the CPU?

Not problematically so. 
 

I don’t run mine this hot but that’s still far away from throttling. 

[simbol 5,767]

12 minutes ago, psolk said:

Until Alder Lake that was...  Now with -P cores and -E cores not all cores run at the same level.  So if core 9 is a -E core on Alder Lake you would be running at 3.6 instead of 5.1   

 

Right so intel has ruined our lives one more time.. sigh..

S.

[Juliett Alfa Romeo 508]

Speaking of which, is Intel still the best alternative for P3D or is AMD already worth it?

[flycln 435]

3 hours ago, simbol said:

Right so intel has ruined our lives one more time.. sigh..

S.

Why? Works just fine for me. After years of almost standstill, Alder Lake is amazing. 

Edited January 28, 2022 by flycln

[FBW737 511]

OK, so there is another explanation for this:

anonymous image hosting

 

[flycln 435]

Bad thermal compound application. 
 

I’ve never seen such huge differences when all cores are at 100% load. 

Edited January 28, 2022 by flycln