Long stutters with FSL and hyperthreading on/Affinity Mask

[chapstick 2,757]

My system is a 5600x (6c/12t) with a 3080ti. Recently, I started getting long stutters/pauses in the FSL A32X, about 2 seconds every couple of minutes, especially in scenery-dense areas around airports on departure/arrival. 

It only seems to happen when I have SMT/hyperthreading turned on and using the following AM:

[JobScheduler]
AffinityMask=4053
P3DCoreAffinityMask=4053
MainThreadScheduler=0
RenderThreadScheduler=1
FrameWorkerThreadScheduler=2

 

If I turn SMT off, so just 6 cores total, and let P3D rebuild the AM to default, the stutter goes away:

[JobScheduler]
AffinityMask=63
P3DCoreAffinityMask=63
MainThreadScheduler=0
RenderThreadScheduler=2
FrameWorkerThreadScheduler=4

Is there anything I can do to be able to have SMT on and stop this stuttering? 

 

 

 

[blaunarwal 432]

Why would you want to use SMT if it's not good for P3D?

 

[chapstick 2,757]

36 minutes ago, blaunarwal said:

Why would you want to use SMT if it's not good for P3D?

 

Well supposedly you can achieve the same or better perf with SMT/HT on in P3D these days, and I'd prefer to keep it on for other apps and workloads besides P3D. I just have to figure out why FSL in particular doesn't like it on my system. 

[Bob Scott 7,721]

You could try using an affinity mask that limits P3D to one virtual CPU per physical core (e.g. 1365 = 010101010101), which effectively disables SMT for P3D, but leaves it available for everything else running on the computer.

 

[Michael Moe 495]

You could try to move the umpolicy away from the FSL folders (there are several if you have expansions packs)

Say no to rebuild when launching P3D and see if it works for you.

Michael Moe

[blaunarwal 432]

4 hours ago, Chapstick said:

Well supposedly you can achieve the same or better perf with SMT/HT

Well, I think you proved, you can´t.

[sonny147 579]

Try removing FSL UM policy , worth a try 

[jcomm 5,938]

What's UM Policy ?

How can it be turned on / off ?

[sonny147 579]

4 minutes ago, jcomm said:

What's UM Policy ?

How can it be turned on / off ?

C/Users/YOU/Documents/Prepared3D Addon-ons/FSLabs/A320/Data/UMPolicy

Cut and paste to desktop( do not delete yet). Do that for all your FSL aircraft. i only fly 320 SL so i have removed the UM for that aircraft. I read on this and other forums there is a conflict with p3d affinity, give it a try !

[jcomm 5,938]

Ah !  That !!!

I only have P3D installed a couple, at most 3 times a year, for the FSL and Active Sky only, and everytime I think I have seen that "massage" that supposedly the FSL installer does to my process affinity for P3D.exe. 

So that's it - there used to be a way to not enable it during install, but the last time I installed a 1 month professional dev license I got the idea I was no longer able to opt out from it 😕

So, what you pointed me to is very useful ! Thanks !

I am also ( just like the OP ) on a Ryzem 5600x, 6 core / 12 SMT vCPUs.

👍

I also would like to take this chance to ask for yet another suggestion:

- Coupled with that UMPolicy "blockage", what should I set in my 

[JobScheduler]

section, given I'm on a 6 core CPU with SMT enabled ?

THANKS !

Edited April 10, 2022 by jcomm

[sonny147 579]

have A LOOK IN THERE

[him225 51]

If you look at the task manager cpu usage with fsl a32x, all cores enabled by the p3d main affinity mask entry are being used equally, regardless of the other new p3d cpu affinity settings you put. This indicates there is probable issue with FSL cpu optimization, as normal p3d cpu usage should not look like that, and indicates lot of thread bouncing among cores made worse with HT enabled. That may be causing thread stalling and the long stutters, also resulting in p3d clock increasingly lagging behind. In normal conditions only the main job running core should have uniformely highest cpu use while others much lesser and variable when moving, which is the case seen with most other aircrafts.

[micstatic 4,319]

so does the fslabs UMP only make changes when running fslabs aircraft?

[chapstick 2,757]

5 hours ago, sonny147 said:

Try removing FSL UM policy , worth a try 

Unfortunately, the stutter is still present without the UMPolicy files. It's very strange because it wasn't doing this a week ago. 

[sonny147 579]

any new software ?