Fellow Simmers,

 

Just wanted to share this here as I've seen many experiencing this issue with PMDG aircraft.  I've experienced this with many other add-on aircraft as well.

 

After experiencing the issue of FSX freezing in-flight for 5-10 minutes then resuming many times over the last few years, I've finally found a workaround that will eliminate it completely. I'm not calling it a fix because it's definitely some sort of bug in FSX that conflicts with a Windows OS resource or service.

The short answer is, exclude "Core 0" (including the hyper-threading on that core if applicable) on all multi-core processors from FSX by setting an affinitymask. If you only have a single core processor, not much can be done(maybe consider upgrading to something newer ).

I've done lots of testing and long flights using and not using "Core 0" and every time the tests are as predicted. Freezes when utilizing and does not freeze when excluded.

If you get some other result after a freeze other than your flight resuming (ie crash to desktop - CTD), that is a completely different issue and this workaround probably will not resolve it. You can try it but no guarantees.

A good tool to calculate your affinity mask would here:
http://www.gatwick-fsg.org.uk/affinitymask.aspx?SubMenuItem=hardware

For my Core i7 2600k (hyper-threading enabled) I get the best results using:

[JOBSCHEDULER]
AffinityMask=244

In conclusion, all I can say is give it a try if you are experiencing those annoying freezes. Make sure you make a backup of your fsx.cfg file before making any changes.

Good luck!

Are these 5 to 10 minute freezes or 5 to 10 seconds?  minutes seems like something really going wrong and not something I have seen but I have seen the freezes anywhere from 2 to 10 seconds.  I actually narrowed it down to Microsoft Security Essentials scan and once I excluded real time protection it went away.  I am guessing excluding core 0 is having the same exclusion effect.

Are these 5 to 10 minute freezes or 5 to 10 seconds?  minutes seems like something really going wrong and not something I have seen but I have seen the freezes anywhere from 2 to 10 seconds.  I actually narrowed it down to Microsoft Security Essentials scan and once I excluded real time protection it went away.  I am guessing excluding core 0 is having the same exclusion effect.

 

Definitely minutes.

Why 244 and not 84 as usual?

Yes....it's a ten minute freeze with sound still running in the background....happened to me twice during a 2 hour flight...patience in needed, then the flight resumes as if nothing happened. Can confirm i have been using a mask of 248 and haven't experienced freezes since.....

Experienced this more than a few times in the NGX, but I was already "excluding" Core 0 (running an i7 non-HT, so Affinity Mask of 14), when it occurred (MSE already excluded as well), so it sounds like yet another YMMV situation particular to each person's setup...

 

Regards,

 

Chris B.

PMDG introduction document for the Boeing 777, p. 36:

 

"(...) What this setting does is restrict FSX to using the second through fourth
physical CPU cores for its extended multithreading, which is used for
terrain and AI object loading. (Note that the main FSX thread always runs
on the first physical core regardless of this setting.)"

 

Are you basically confirming this?

The way I understand it is the main thread will always run on the lowest assigned core......so setting an afffinity mask to exclude core '0' will cause the main thread to run on the next lowest core leaving core '0' free.

Not to muddy the waters as it were, but my understanding was that the FSX main thread (and therefore the flight model - for the default aircraft anyway), always runs on Core 0 regardless - setting the affinity mask tells FSX which other other cores to use for texture rendering and the like, with each successive Core generally seeing less and less utilization as you move up numerically - this scheme at least appears to be how things play out on my system, and on my friend's 6 core system as well, where Cores 4 & 5 weren't seeing much action at all - it is also my understanding that 6 physical Cores is all FSX can actually ever be aware of anyway...

 

 

Chris B.

Not all appHangs (the error name for FSX freezing for 5-10 min) can be fixed with the affinity mask, and using or not using core 0 will not always solve it.

 

I solved my appHang problem when I migrated from Vista to Win7 (not too distant past in my case), but having Win7 doesn't make you immune to the problem.  Just saying the affinity mask is a good possible solution but not a fix to all appHangs.  Using the affinity mask with FSX is recommend by PMDG and I always adhered to it.

 

P3D is smart enough to set it's own affinity during runtime.  All I do with it is let 'er rip but move ASN (and anything else that is active) off of core 0.  This is easy to do with Process Explorer and it seems to work pretty good and is recommended in L-M's own forum.

Why 244 and not 84 as usual?

 

The reason I use 244 is I have less stuttering when use the logical core on core 1 and both the logical core and thread on core's 2 & 3.   This helps by dedicating the logical core 1 as FSX primary processor and with the progressive scenery rendering on core's 2 & 3.

Not to muddy the waters as it were, but my understanding was that the FSX main thread (and therefore the flight model - for the default aircraft anyway), always runs on Core 0 regardless - setting the affinity mask tells FSX which other other cores to use for texture rendering and the like, with each successive Core generally seeing less and less utilization as you move up numerically - this scheme at least appears to be how things play out on my system, and on my friend's 6 core system as well, where Cores 4 & 5 weren't seeing much action at all - it is also my understanding that 6 physical Cores is all FSX can actually ever be aware of anyway...

 

 

Chris B.

 

A properly set affinitymask will indeed redirect FSX's primary process to the next available core.  It can also be used to enable or disable other core's/threads for use.  Set it, run FSX then bring up the Windows task manager and view the performance tab.  You'll see the graphs and utilization of each core/thread.  From left to right starts at Core 0.  You will notice that the primary core FSX uses will usually be in the 90% or more when running.  Give it a try.

In conclusion, all I can say is give it a try if you are experiencing those annoying freezes.

Yes and no.

I use DX10 with fixer and although “Hyperthreading always off” is preached by many, for DX10, enabling Hyperthreading in the system and adding AffinityMask to fsx.cfg, framerate and stability appear to improve by 2-4% - particularly beneficial for aircraft that use processes outside of FSX (MJC Dash-8, PMDG etc.). Here are some example values:

4 Core HT off 14 1110 3 Main threads 1 worker

4 Core HT off 12 1100 2 Main threads 2 workers

4 Core HT on 254 1111 1110 3 Main threads 1 worker

4 Core HT on 252 1111 1100 2 Main threads 2 workers

 

Infact with PMDG aircraft I have no freeze, but with Airbus X at every flight I have a 5 to 8 min. freeze.

Yes and no.

I use DX10 with fixer and although “Hyperthreading always off” is preached by many, for DX10, enabling Hyperthreading in the system and adding AffinityMask to fsx.cfg, framerate and stability appear to improve by 2-4% - particularly beneficial for aircraft that use processes outside of FSX (MJC Dash-8, PMDG etc.). Here are some example values:

4 Core HT off 14 1110 3 Main threads 1 worker

4 Core HT off 12 1100 2 Main threads 2 workers

4 Core HT on 254 1111 1110 3 Main threads 1 worker

4 Core HT on 252 1111 1100 2 Main threads 2 workers

 

Infact with PMDG aircraft I have no freeze, but with Airbus X at every flight I have a 5 to 8 min. freeze.

 

Hyperthreading has always worked better for me as well.  Much smoother experience.  Here's a breakdown of my affinitymask setting:

 

4 Core HT on: 244 - 11 11 01 00

 

Break it down even more, reading the binary conversion from left to right:

 

11 (Core3 Thread/Logical)

11 (Core2 Thread/Logical)

01 (Core1 Logical)

00 (Core0 Neither Thread nor Logical core being used)

 

As you can see here I've dedicated Core1 to FSX's main process/thread using the logical core and excluding the Thread(HT).  Core0 will not be used by FSX.

Using 244 so far so good, ni hickups, only slight micro stutters in A2A 182 as usual. Test 2 will be in NGX. Backup is 254, just in case. 84 didn't worked so well for me I think.