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RaptyrOne

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

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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.


GregH

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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..


Bert

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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.


Frank L.T

 

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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


Frank L.T

 

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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.


John

Rig: Gigabyte B550 AORUS Master Motherboard, AMD Ryzen 7 3800XT CPU, 32GB DDR4 Ram, Gigabyte RTX 2070 Super Graphics,  Samsung Odyssey  wide view display (5120 x 1440 pixels) with VSYNC on.

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The only thing additional CPU cores are good for in FSX is scenery loading. There is a mistaken assumption that many people make that more cores somehow offloads more off the main thread that FSX runs on.

 

Guess what it doesn't.

 

That is why heavy duty aircraft like PMDG  will gut your FPS in VC compared to an outside view because all those displays and gauges choke the main thread.

 

There are exceptions to this like the FDE used by Majestic in their Q400 or iFly cockpit builder edition running remote executable gauges on another PC, but they are few and far between. 

 

I know Phil Taylor said back in the day that FSX will up to 255 cores or whatever but there comes a tipping point where more is not better and the overhead of splitting scenery loading over a bunch of cores really just will not do anything for you because the hold up is the main thread which is still only running on 1 core. Thats why FSX is so CPU bound and responds so well to overclocking.

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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.

 

 

Uhmmm.. maybe time to re-read Phil Taylor's remarks..  As of FSX SP2:

 

Texture loading is actually done by the cores that follow the main FSX rendering core..

 

So, with AM=14

 

Core0 free for Windows and other tasks (+a small main FSX footprint)

 

Core1 dedicated to FSX rendering = the main FSX load

 

Core2 and 3 dedicated to texture loading

 

B)


Bert

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I have note in my FSX configuration file which was an early recommendation from Avsim as follows:

 

For a quad core with HT off use 14

For a quad core with HT on use 84

 

I started off with 14 for a few years and now run 84. with no apparent FSX performance difference between the two. 


John

Rig: Gigabyte B550 AORUS Master Motherboard, AMD Ryzen 7 3800XT CPU, 32GB DDR4 Ram, Gigabyte RTX 2070 Super Graphics,  Samsung Odyssey  wide view display (5120 x 1440 pixels) with VSYNC on.

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I have note in my FSX configuration file which was an early recommendation from Avsim as follows:

 

For a quad core with HT off use 14

For a quad core with HT on use 84

 

 

That is still valid.. and you should not see any performance difference, since they are essentially the same.


Bert

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