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simmerhead

AffinityMask needed to get all cores working

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I noticed when benchmarking and tuning my settings that P3D2 by default only used three of my four i7 2700K cores.

 

I had to insert the AffinityMask=15 tweak to get all four cores working to the max as they do in P3D1.4.

 

Just a head's up!

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Ok am learning about this, but why 15? I thought for a quad core it was a value of 14?

 

Sent from my Mobile thing

 

 

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Ok am learning about this, but why 15? I thought for a quad core it was a value of 14?

 

Sent from my Mobile thing

 

I think by default it is 1110 (14) so to get it using all 4 cores it needs 1111(15). 0=core not used, 1=core used. The number furthest to the right represents the first core (core 0).

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I think its:

 

in binary 15 = 1111   

 

this is broken as one in the one's place

1 in the two's place

1 in the four's place

and 1 in the 8ths place

 

add them up 1+2+4+8 = 15

 

each 1 acts as a switch to turn on each core..

 

 

I'm just guessing.. someone who really knows.. chime in.

 

edit:;; I see someone beat me.

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Affinity masks means only use the cores you select.

 

If you have 4 cores selecting all four will make sod all difference.

 

Since win 7 I have seen no proof of any benefit using affinity masks.

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LM have automatically shifted v2 onto core 1,2 and 3 leaving 0 for OS and drivers.

 

Adding AM =14 will do nothing!

 

Adding am=15 will replicate what fsx does without the affinity mask entry.

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thanks everyone, will make the change in my setup

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LM have automatically shifted v2 onto core 1,2 and 3 leaving 0 for OS and drivers.

 

Adding AM =14 will do nothing!

 

Adding am=15 will replicate what fsx does without the affinity mask entry.

 

Yep, I check usage between FSX and P3D, my results matched exactly that statement.  I found no benefit to this tweak in P3D (only in a very short comparison), since by default it's running the equivalent on AM = 14.

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Guys,

 

Using the Converter at the following website removes all speculation.  Just remember....

 

1. i5's don't have Hyper-threading, so it's only 4 cores (thus 4 binary digits... 1110 is decimal 14).

2. Some folks will tell you that FSX/P3D runs better without Hyper-threading. This depends on whether or not you're running other programs on the same computer, and since each computer/setup is different, each i7 user will simply have to test it for themselves. End of story on that one, just get off the couch and test it both ways. If Hyper-threading is best on your system, then you're coding 4 cores as 8 threads (Example: Binary 11111100, which is decimal 252. Binary 11111110 is decimal 254). If Hyper-threading, some may be able to get away with using all threads except the last one (11111110). 

3. If you are running programs other than FSX/P3D on the same computer, they will need room to breath, so leave the last core free (see below).

4. For FSX (and maybe P3D), Core 0 (or threads 0/1) will always be used, so if you set Affinity Mask to use the last three cores then you're essentially setting to use all cores.

 

I've tested Hyper-threading and non-HT on an i7-920, i7-930, i7-960 and i74770K, and had guys that I know and trust do the same over the long term.  I'll say once again that each person has to test this for themselves in order to nail down what works best for them given the software they run/don't run in concert with FSX/P3D.

 

Sincerely hope this helps anyone looking into this..

 

Here's the converter:  http://www.easycalculation.com/decimal-converter.php

 

 

 

Dave

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Ok so back to square one. If I have an i5, I dont need an am entry, as P3D already sets the value at 14.

So what does a value of 15 actually do and why is it making a difference?

 

Sent from my Mobile thing

 

 

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Ok so back to square one. If I have an i5, I dont need an am entry, as P3D already sets the value at 14.

So what does a value of 15 actually do and why is it making a difference?

 

Sent from my Mobile thing

 

15 should use all your cores as opposed to 14 which only uses cores 1,2 and 3 where core 0 is not used. But I don't know if this has any performance advantage.

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Ok so back to square one. If I have an i5, I dont need an am entry, as P3D already sets the value at 14.

So what does a value of 15 actually do and why is it making a difference?

 

Sent from my Mobile thing

 

It turns on all FOUR cores, not just the THREE last cores. I prefer to have all four cores working until  I get a better GPU than I can offload to with Tessellation.

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Ok thanks guys, sorry if I sounded a bit dense, it has been a loooong week. Looks forward to some flying. Thanks again.

 

Sent from my Mobile thing

 

 

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Thanks for the chart Roman! I was running AM at 84, but will give 252 and 255 a try...

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Just for the record I have never noticed a perceivable difference with HT on or off in FSX on my system, so I have kept it enabled on my 2700K with AF=84.

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