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Question on 6 Core Affinity with 777

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Hi all, I would appreciate any guidance on setting the affinity on the processor check boxes,as you can see,I am running a 6 core with Hyper threading,and no AF entry in P3D cfg. I don't know how all those check boxes got checked.

Thanks!

 

http://i177.photobucket.com/albums/w205/B1900Mech/Lockheed%20P3D/P3D%20Issues/AF.jpg

 


Jim Driscoll


 

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This is a P3D question that might best be served in their forum; however, i believe the P3D executable will use all available logical/physical cores by default.  I use the affinity setting simply to reserve core 0 for other applications that I run during a session.


Dan Downs KCRP

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4 cores, HT disabled?

 

OP uses 6 cores with HT enabled. AF=1364 sounds just about right for him.

PMDG state in the manual the reason why. I dont have it handy here but to sum it up, it fixes freezing issues they cannot explain why

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PMDG state in the manual the reason why. I dont have it handy here but to sum it up, it fixes freezing issues they cannot explain why

Full names in the PMDG forums please.

 

It entirely depends on number of physical and logical cores, and it's simple binary counting. No black art.  However, note that P3D will use all available threads and the only value that using the affinity mask provides is blocking core 0, which I do.


Dan Downs KCRP

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PMDG state in the manual the reason why. I dont have it handy here but to sum it up, it fixes freezing issues they cannot explain why

 

 

You're correct; PMDG state that AF=14 should even be used with 6 core processors, or with HT enabled, in order to eliminate freezes. With AF=14 FSX would use only 4 cores even in a 6, 8 or 12 core environment.

 

If freezes are no issue, different AF settings would make sense for performance reasons, though.


What happened to AVSIM

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1364 (5 Logical Processors) is a good call, keeping threads to single LPs per core. Can also try 2720 (4 LPs), or 2688 (3 LPs), and these reverse the order the LPs are loaded on the cores, worth a test. Remember that P3D and FSX need 3 cores at minimum for best results. Going for maximum threads can be a mistake, and an excess of threads synchronizing with the main thread can slow it down. Also each 32bit thread on a 64bit O/S consumes more memory. As PMDG state going for AM=14 generally will provide 3 LPs whatever CPU these days and get round any problems.


Steve Waite: Engineer at codelegend.com

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Best performance with AM=244 here with i7 4core HT on.... (works better than 84 for me)

AM 14 is quite a performance roller coaster on my system...


Claus KUEPPER

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Best performance with AM=244 here with i7 4core HT on.... (works better than 84 for me)

AM 14 is quite a performance roller coaster on my system...

How about 170?


Steve Waite: Engineer at codelegend.com

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How about 170?

just using 4 non physical processors sounds "odd" to me. Although 170 would also keep #0 clean... I will give it a try and see how intel turboboost tec handles it...

 

with AM 244 I know that the only degradation (9FPS) occurs on peaks caused by UT2 and ASN in extreme weather during dusk/dawn every 5 min for 1 second...


Claus KUEPPER

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just using 4 non physical processors sounds "odd" to me. Although 170 would also keep #0 clean... I will give it a try and see how intel turboboost tec handles it...

 

with AM 244 I know that the only degradation (9FPS) occurs on peaks caused by UT2 and ASN in extreme weather during dusk/dawn every 5 min for 1 second...

244 (11110100) demonstrates some good ideas and you probably found an optimum there. As you quite rightly intimate, the problem is not just one of spreading the load over the available cores but also it's keeping busy processes off the core with the first FS thread. With 244=(11,11,01,00) the two paired up cores (11,11) with the secondary FSX threads, mean they are always fully utilised. Although core 0 (00) is free for other threads starting up, core 1 (01) with the main FS thread, has a higher probability of being hit by other threads starting than the two pared up secondary FS threads. Which sounds like what you may be describing with ASN coming in with the weather updates. The two paired threads also use double the resources over one pair on two cores, and double the synchronizing with the main thread, and may be underutilised. Also worth trying on 4 core with HT=ON is 42 and 21, and maybe try 168 which is like 84 but with reversed LP allocations.


Steve Waite: Engineer at codelegend.com

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Thanks,I read the 777 P3D introduction,but didn't recall seeing the affinity 14 suggestion. I have all my sliders at 1/2 settings,and cant even make a KBOS to KPHL flight without freezing up,that is with fresh install on an external solid state hard drive (/X:\Lockheed Martin\Prepar3D v2)with MTX 54.C ,Flytampa KBOS and SunSky Jet KPHL. I am using all the tweaks on this forum and whats in the P3D docs. Off to try AF14,thanks again, I dream of sloped runways!


Jim Driscoll


 

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Remember if you have HT on (CPU hyperthreading) then the equivalent to 14 is 84, or 168.


Steve Waite: Engineer at codelegend.com

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