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ghutcheon

A fresh debate on Affinity Mask and modern quad core CPU's

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There are many posts on these and other forums discussing AffinityMask. Been thrashed to death, almost. Until now I have taken note of them but never incorporated them into my FSX.cfg, mainly because there are way too many opinions on what is right and whether it makes for a better experience or a worse experience in the sim. "If in doubt, pull out" is what I say :-) pretty sure many opinions are placebo.

 

A recent in-flight 8 minute freezing problem seems to have been fixed by using the AffinityMask setting however, after it was suggested in another forum here on Avsim. Still early days but no freezes since going with a setting of 252.

 

Hyper Threading on or off? Why turn it off unless you are pushing your CPU to its overclocking and temperature limit? Why restrict your expensive processor to only 4 cores just because FSX is unable to make full (any?) use of it? It is not like your sim will run slower with HT off? But the rest of your computing on that computer might. Either FSX can see the virtual cores or it can't. So I run with HT on....

 

Then comes the question, do you go with an AM setting that turns off just the first main core (255) or both the first core and it's virtual partner (252)? Surely it matters as we are reserving this first core for Windows and it's processes and Windows CAN see the virtual core even if FSX can't?

 

Why is it suggested that 84 be used with HT on? Does this figure not totally ignore the virtual cores? Akin to turning HT off as far as the simulator is concerned? If FSX does not see virtual cores and Windows cannot make use of these virtual cores while the sim is running, then surely 84 and 252 are the exact same result?

 

I know the suggestion to 'experiment and see what works for you' but I don't like to experiment, I like to fly :-) Plus I feel better not second guessing myself on which setting "might" be better than the next - placebo improvements or otherwise can easily get the better of all of us from time to time.

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Try to keep in mind what works for one may be instant death to another.  Minor experimentation,

 

if done in small steps with plenty of documentation,  could yield great rewards.

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A small amount of searching will answer almost all of your questions.

 

As you mention in your first paragraph, this topic has been thrashed to death.

 

Cheers,

Mark

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There are three schools of thought on this.. and that is why you see endless debates..

 

Here is an attempt to describe the three theories:

 

1.  FSX does not support HT and runs better if only one thread per core is in use, and if FSX does not run on the Windows core,  so either turn off HT in the BIOS and use AM=14 or simulate this with HT turned on which leads to AM=84

 

2. Even though FSX does not support HT, Windows does - so why not give Windows lots of texture loading cores to schedule threads on, the more the better!  This leads to HT=on and AM=254 or 252 etc

 

3. Ignore FSX preferences, Windows 7 is smart enough to schedule work efficiently,  and I paid for (four) eight cores, so lets put them all to work, which leads to AM = 15 or 255.

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3. Ignore FSX preferences, Windows 7 is smart enough to schedule work efficiently,  and I payed for (four) eight cores, so lets put them all to work, which leads to AM = 15 or 255.

 

I think this leads to micro-stuttering.

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..and let the debate begin  :rolleyes:

So very dry...so very good!...from a fellow Canadian

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..and let the debate begin  :rolleyes:

 

lol.

 

Throw in other applications you may be running (weather engine, FS INN/ Sqawkbox, ACARS, etc) into the mix as well for those not fortunate enough to have a network for simming.

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I think we should have a poll and see what everyone out here is using? :-)

 

... And I recon that 252 also leads to micro stuttering.

 

Is AM=15 not the same as no entry in the cfg at all?

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I have left it out completely! No need to clutter up the CFG file.....

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I have left it out completely! No need to clutter up the CFG file.....

Exactly why fill the cfg. With these "bloatware" tweaks not knowing what they are doing in FSX, then complain when things go wrong, all Placebo to me.

I can add to the debate that HT on lead to stutters for me, may work wonders for others...

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Agree with you McLaren and 777.

 

I am not using these tweaks: Affinity Mask,  the Bufferpools tweak, Fibre Frame Time Fraction etc etc... - because they are at best placebo and at worst create other issues. HOWEVER my problem actually appears to be solved by applying the AM tweak. (Freezing up in flight for a couple minutes at random.)

 

Of course, it may well be that another problem is causing this problem and now I am fixing the secondary problem which might lead to more problems.......

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I really shouldn't encourage debate in this old topic that has been discussed ad nauseam for almost a decade, but AF, BP, and FFTF are hardly "bloatware" or placebo tweaks as was suggested. Plenty of verifiable evidence that these are quite effective.

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Agree with you McLaren and 777.

 

I am not using these tweaks: Affinity Mask,  the Bufferpools tweak, Fibre Frame Time Fraction etc etc... - because they are at best placebo and at worst create other issues. HOWEVER my problem actually appears to be solved by applying the AM tweak. (Freezing up in flight for a couple minutes at random.)

 

Of course, it may well be that another problem is causing this problem and now I am fixing the secondary problem which might lead to more problems.......

 

Not sure what aircraft/situation you are experiencing this with but I had the same issue with the Majestic Dash8 and I thought it had to do with AM/Lack of AM setting. What it ended up being was FSUIPC autosave. 

 

 

I really shouldn't encourage debate in this old topic that has been discussed ad nauseam for almost a decade, but AF, BP, and FFTF are hardly "bloatware" or placebo tweaks as was suggested. Plenty of verifiable evidence that these are quite effective.

 

 

Is this the case with newer hardware? I have done a fair amount of testing with my rig (see specs on the left) and have found that my best experience comes from no tweaks in the CFG other than HighMem and DsiablePreLoad. I also have 2048 textures for FSDT airports and LOD=6.5 from an eye-candy standpoint. 

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BP and FFTF are as I understand it more suitable to slightly older hardware. Convinced it does nothing for my system in terms of smoothness or performance - I7-4770K GTX780 and more RAM than FSX knows what to do with.

 

I guess this just proves what I am getting at though (and I say this with respect to all) that there is no consensus on what is truly the perfect setting or set of tweaks to use. We all simply experiment and then go with what we perceive (rightly or wrongly) to be best for our particular set up. I hazard to say that 5 different people tweaking the same PC would end up with different tweak combinations, each believing that they have the best solution. Anyway, still no freeze up with the AF tweak.... Holding thumbs.

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I'm going against common sense; since upping FFTF to 0.44 or even 0.55 I NEVER get blurries even when flying low at high speed, and I see no additional stuttering. To me this setting DOES make a difference, as well as giving all 8 cores to FSX with AM=255.

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I'm going against common sense; since upping FFTF to 0.44 or even 0.55 I NEVER get blurries even when flying low at high speed, and I see no additional stuttering.

That does not go against common sense - you are giving more time to texture loading and less to rendering..  that is exactly what FFTF is documented as doing..

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pheeewww! well, that seems to be what works best on my system! :smile:

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Out of curiosity, how can I tell if hyper-threading is on or off on either of my rigs (4770 and a 2700). I've checked the BIOS at startup and can't even find the word mentioned in any of the lists. Thanks.

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Out of curiosity, how can I tell if hyper-threading is on or off on either of my rigs (4770 and a 2700). I've checked the BIOS at startup and can't even find the word mentioned in any of the lists. Thanks.

 

Simply open task manager and check the Performance tab. If you have 8 graphs in the CPU Usage History section, HT is enabled. If there's just 4 of them, it's disabled

I'm going against common sense; since upping FFTF to 0.44 or even 0.55 I NEVER get blurries even when flying low at high speed, and I see no additional stuttering. To me this setting DOES make a difference, as well as giving all 8 cores to FSX with AM=255.

 

Are you using 255 on a Phenom X4 quad core or are your specs outdated?  

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Ah, you caught me there! I'm now on a FX-8350, and I'm seeing full utilization of all 8 cores with AF=255. Need to update my specs.

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Simply open task manager and check the Performance tab. If you have 8 graphs in the CPU Usage History section, HT is enabled. If there's just 4 of them, it's disabled

 

That was easy, my 4770 is showing 8 cores, the 2700 4 cores. Thanks

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Let's remember the origins of the Affinity Mask and FSX. IIRC Phil Taylor, when FSX first hit the market, let it be known that FSX used CPU 0 as the only path for FSX texture loading and at that time texture loading was a major cause of stutters in FSX. So to give the texture loading maximum throughput the Affinity mask was used to keep CPU 0 free of any activity except texture loading. It was further recommended to turn multi threading off so that CPU 0 wasn't time sharing between threads.

 

However, times have changed and both hardware and software have improved considerably. So it would be a matter of debate wether or not the original reasons for the  Affinity mask are still relevant with use of current hardware and software technology. In particular the advent of stock CPUs capable of running in the high 4GHZ plus range and SSDs. These technologies may also cause the FFTF values to be worthy of further scrutiny and experimentation. 

 

We all know that FSX is a very difficult environment to benchmark, so comparisons between different users setups is very difficult and time consuming and I am a firm believer that a "one size fits all' solution is highly improbable.

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