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CPU Affinity with P3D v4

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I've seen varying opinions on using CPU affinity with v4. Some have said that because of new dynamic controls built in to  P3D itself, manual affinity is no longer needed (I use ProcessLasso to assign CPU affinity rather than changing the .cfg affinity mask). Right now I am running v4 on a 4-processor system (don't laugh. It has actually been working VERY well, way better than FSX was on the same system). Based on the old rules of affinity that I had read, I made it so that P3D is set to use CPU's 1, 2, and 3 and all of my add-ons use CPU 0. So far so good. But, I was wondering if I should just remove the affinity altogether and let it do it's thing.

What has been your experience with v4? What would you recommend?

Connor Pack, United States

P3Dv4, ORBX, FS2Crew, GSX, Active Sky v4 + ASCA, PMDG 737, Navigraph Charts + Data, TOPCAT, PFPX, UTLive, FSFX Packages, Flightbeam Airports.

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I'm in your boat with a 4790k and use Lasso on cores 1-3 with no Hyperthreading.  Works great for me and I'm going to leave mine alone.

7 hours ago, cleonpack93 said:

But, I was wondering if I should just remove the affinity altogether and let it do it's thing.

Try it an you will see. My experience (4 core and 8 core) tells me P3Dv4 does not need AM/PL.

- Harry 

9800x3D (Strix x870e-E)  -  64GB RAM (DDR5 6000, CL 30)  -  RTX 5090, 34'' 1440p OLED HDR  -  Windows 11 Pro (1TB M.2)  -  MSFS 2024 (MS Store, 4TB M.2).

  • Commercial Member

I tried AM with 4.1 as i was used to do it in FSX.. BUT there is no really any need.

I fly with everything in one Machine with 2 Monitors:

  • P3Dv4.1
  • Active Sky + ASCA
  • FSrealtime
  • Charts Navigraph (mostly web based)
  • Chrome
  • vPilot (i fly exclusively online)

...and my machine hansles it very well (see it in the sig)...So i wouldn;t bother with Affinity mask.

__________________________________________________________________________________________
My FS Photos - My MSFS Settings - i7-14700K / 64GB RAM / MSI 4070 Ti SUPER / 1440p
 

7 hours ago, cleonpack93 said:

What has been your experience with v4? What would you recommend?

It works like allways, but you may get blurry textures. On 4 cores CPU with no AM - core 2 and 3 are loading textures, with AM=14 only core 3, and that's not enough on my system. I'm not using it with P3Dv4 becouse of this

Zeljko Budovic

I haven't found any need to mess with the cfg at all, including AM. Smooth like silk with very high settings on my i6700k and gtx1070. I do have dynamic lighting and high res ground textures off, though.

 

 

Prepar3D v4.1
i7 3770K @4.7Ghz (4 cores) running with HT
(980ti - 16GB Ram - Win10 updated - Latest Nvidia Drivers)

From my tests i've found out that setting AM to 252 (first logical and first thread for the apps like ai monitoring, external gauges, Littlenavmap, weather engine, Chaseplane, ecc..., and all other logical and threads on P3D) makes P3D running with slighlty better FPS, but most important a lot of less stuttering.

Logical 0 and thread 0: 10%-25% for the apps

Logical 1: full 100% for rendering. Thread 1: 70%-80%

Logical 2 and 3, Thread 2 and 3: 90%-100% (all other P3D tasks)

Hope this helps.

AFFINITY_MASK - Just say no!

cheers bs

AMD RYZEN 9 5900X 12 CORE CPU - ZOTAC RTX 3060Ti GPU - NZXT H510i ELITE CASE - EVO M.2 970 500GB DRIVE - 32GB XTREEM 4000 MEM - XPG GOLD 80+ 650 WATT PS - NZXT 280 HYBRID COOLER

Ok W

3 hours ago, bean_sprout said:

AFFINITY_MASK - Just say no!

cheers bs

ok well... damn... before it was FSX... now P3D... it makes me go crazy....

After more testing, HT OFF and no AF, 3-4 fps more and even less stuttering.

DAMN.

This is not a flight simulator. It is a testing-benchmarking tool :D

Considering i ran P3D for one year, 10 months it was running for benchmarking and testing.

...

  • Author

I decided to turn affinity off in ProcessLasso and saw an overall reduction in stutters. So there ya go I guess haha

Connor Pack, United States

P3Dv4, ORBX, FS2Crew, GSX, Active Sky v4 + ASCA, PMDG 737, Navigraph Charts + Data, TOPCAT, PFPX, UTLive, FSFX Packages, Flightbeam Airports.

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The only AF mask that works for me (6700K, HT on) is:

[JOBSCHEDULER]
AffinityMask=253

which does nothing else then mask out the first logical core as the main thread runs on Core 0 and I wanted to get rid of everything else on Core 0/1. This makes the sim more fluid for me, but does not give more FPS. All other settings don't really work for me. As this is highly dependent on all other software that is running it is hard to find the AF mask that suites the best for one personally. :-(

+1 

[JOBSCHEDULER]
AffinityMask=253

CPU: [email protected], HT on.

The only other tweak I use, and it actually makes a bigger difference, is:

[TERRAIN]
TEXTURE_SIZE_EXP=9

GPU: GTX1070

 

Bert

+1 

[JOBSCHEDULER]
AffinityMask=253

CPU: [email protected], HT on.

In my case 253 is also the best value at p3d launch.
But it is also interesting after the launch to set AF to 255.
All cores work without saturation.
You can watch this video to know how to do that :

You can also do this automatically.
In my case I launch p3d with a bat file and after 60 seconds I set AF at 255.

Here is the content of my file start_p3d.bat

cmd.exe /c start "Prepar3D" "C:\Program Files\Lockheed Martin\Prepar3D v4\Prepar3D.exe"
timeout 60 > NUL
PowerShell "$Process = Get-Process Prepar3D; $Process.ProcessorAffinity=255"

But to works the .bat must be launch in administrator mode.

 

Marc

FS2020alpha, P3D v5 - W10 - i7-8700k @4.7GHz - Asus ROG Strix Z370-F Gaming - Corsair Vengeance LPX 32GB DDR4 3000MHz C15 - Asus ROG Strix GTX 1080Ti-O11G-Gaming - Noctua NH-U12S - SSD Samsung 970 Evo M.2 PCIe NVMe 1To - Cooler Master G650M - HP 35" OMEN X 21:9 3440x1440

Affinity mask has no effect on my P3D4 / 7700K which is the way it should be.

 

Cheers
bs

AMD RYZEN 9 5900X 12 CORE CPU - ZOTAC RTX 3060Ti GPU - NZXT H510i ELITE CASE - EVO M.2 970 500GB DRIVE - 32GB XTREEM 4000 MEM - XPG GOLD 80+ 650 WATT PS - NZXT 280 HYBRID COOLER

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