So one more final thought to make your brain hurt

 

So when FSX was developed 2 core machines were the norm and 4 cores were right on the horizon. The ability to move the FSX main thread off core 1 was a big advantage because the OS would default any additional processes to start there.

 

Today with our multicores this is much less of an issue.

 

Enter Windows 7 - starting with Win 7 a new threading model was introduced called "Group Threading". Basically the goal was to remove the 1 core per bit limit introduced in the original NT Kernel code. IOW a 32bit system had a limit of 32 cores and a 64bit system had a limit of 64 cores. Big clients wanted the core limit removed so now with Win 7 (64bit only) systems the max cores is 256.

 

How did MS do it - by rewriting the kernel and using Group Threads which are 64 (virtual and physical) core groupings. So group 0 would be cores 1-64, group 1 would be cores 65-128 and so on. The beauty is that all the old methods of creating threads, affinity masks ectera would still work.

 

Anyway the result is that all threads within a group are shared. IOW on a four core system all four cores are able to work on the same thread and you can add 4 more if HyperThreading is enabled.

 

So by using the AffinityMask setting you are actually creating a thread group and work will be shared amongst all the cores in the group. This explains why we see the HT threads active in task manager when FSX is running on a 64bit Win 7-8 machine with HT enabled.

 

Cheers

jja

Bojote's setting for my Affinity Mask is 5 is that right for i7-2700k, not sure on this AM stuff, thanks.

The problem with affinity mask experimentation with HT on is that that it's hard to quantify what it buys you. For sheer framerates, I think it's pretty clear that clocks still rule which argues strongly for the maximum stable overclock you can achieve, which also means turning HT off. As mentioned in another recent thread, for a variety of reasons I keep my OC modest, have headroom and find (qualitatively) that HT seems to increase smoothness at the same clock. That is, turning HT off and leaving the clock unchanged seems to degrade my experience.

 

Until recently, I've not used affinity mask at all, but I've been playing with it lately and it seems like different masks might favor different situations. Or perhaps I just think they do, as I haven't used good controls in my playing, just seat of the pants impressions. In any case, what is obvious is that the masks do "work" in the sense that they push what FSX is doing to the cores specified, even the "virtual" ones. Whether doing that is worth anything in a modern multi-core HT capable processor is still very much open to question in my mind.

 

Scott

OOOPS Sorry I have HT on.

Bojote's setting for my Affinity Mask is 5 is that right for i7-2700k, not sure on this AM stuff, thanks.

 

What 5 gives you (HT or not in this case) is core 0 and core 2 for FSX - with HT on that means the first two physical cores. As to what's "right", see above. Conventional wisdom says 14 with HT off or 84 with it on, which gives FSX the last 3 physical cores, leaving the first core (and all virtual cores if HT is on) for other stuff to use.

 

Scott

HI Scott think I tried 84 and it was not so good anyway I can give it another try to be sure after work, thanks a lot.

Soooo... I read almost the entire post SAAB340 wrote (which is very interesting by the way !) but since I have a i7 3930k with HT on ( = 12 threads ) I'm still not sure what value I should be using...

It looks like 4081 is working pretty well but it would be great if anyone could confirm this number, or otherwise explain why it is a very bad one.

Even though with 12 cores instead of 8 I don't really think you would see any actual difference while flying anyway....

 

Thanks in advance !

LOL just whip out trusty WinCalc - 4081 = 111111110001. I'm not sure what's up with using core 1 (first bit on the right) . The whole purpose of AffinityMask was to offload work from core 1. Why not try drop the first core with 4080 = 111111110000. Do some tests in high traffic areas. You could also go for the big Kahauna 4094 = 111111111110. Watch your task manager in a high traffic area and see how many of the cores get used. Cheers jja

 

HI Scott think I tried 84 and it was not so good anyway I can give it another try to be sure after work, thanks a lot.

On a 4 Core with HT you would want to do either 11111100 = 252 or 11111110 = 254. Cheers jja

jja looks interesting but what do I exactly place in the AFFINITYMASK line this 11111100 = 252 or this 252 thanks so much.

Im on a i7-3770k @ 4.9Ghz with HT ON and AM = 249 and I am in heaven using TileProxy at 30cm resolutions.

 

I have a better overall sim experience running FSX at 4.9 Ghz HT ON than 5.0Ghz HT OFF.

 

 

 

- Sent from my rooted, Verizon Samsung Galaxy Nexus LTE smartphone via Tapatalk because haters gonna hate.

 

 

Tried the 252 tell yah FSX does load faster and runs smooth but noticing one thing panning outside view get small stutter not sure what that is, thanks JJA nice info.

Cool good to hear it. Cheers jja

I thought the later versions of windows would move threads available cpus to balance resources.

 

I tried various settings in the past but found no benefits.

 

Affinity might have been useful in the past on older cpus/windows but I think it's irrelevant now.

Well, if I understood SAAB340's article correctly, and based on these results, having only 1 thread free is not good at all, so for me 4094 wouldn't give great results.

I also don't understand why 4080 should give me better results than 4081. In the first case you basically have the main fsx thread (the one that's always at 100%) AND a texture loading thread both on the third core, which is not good, whereas with 4081 (or 4084, that doesn't change anything) the main thread will be on it's own core and the 4 remaining ones will be used for textures and terrain.

I have to say though, that the difference between all these values (except 4094) is almost unnoticeable.

 

I'm still curious to know why you suggested these values, because the conclusions SAAB340 came to are more or less the opposite of what you said. So am I missing something ?

Oh and yeah my brain hurts so bad now :lol:

 

Cheers !

Yes take the AF settings with a grain of salt and test them if you want. Point is I too am feeling that the AF mask setting is largely irrelevant and am flying without it while watching cpu activity. Cheers jja