HYPERTHREAD - FSX - i7 and YOU

[NickN]

I would like everyone to add something to their testing...

After going through the HT checks as requested, DISABLE HT in the BIOS but leave the AffinityMask=N edit in the FSX.cfg file and use the value 15 for it and retest for smoother flight.

[jwenham]

Nick, I tried the test and when I did I goot my OOM problem back. I even lowered the usera down as low as you mentioned and still no luck. Then I removed my OC just to see if it would make things better and still no luck. SO for us 32 bit suckers Hyperthreading does not seem to be a option if you have a GPU with a ton of ram on it. Put all my settings back to as they were and all was good again. Will try the Mask now with no HT.

[jwenham]

I would like everyone to add something to their testing...

After going through the HT checks as requested, DISABLE HT in the BIOS but leave the AffinityMask=N edit in the FSX.cfg file and use the value 15 for it and retest for smoother flight.

Did it .... works great, alot smoother for me! What does the 15 do, apply all 4 cores?


Also running OCCT Beta it only shows a 50% CPU usage as does CPUID as well (This is when HT is on)

[wsciutti]

Nick,

Update on AM=15, HT off.

I don't know how you do this

[NickN]

Good.. then AffinityMask=15 with HT DISABLED in the BIOS also worked for you

Thanks!

[NickN]

I would like everyone to add something to their testing...

After going through the HT checks as requested, DISABLE HT in the BIOS but leave the AffinityMask=N edit in the FSX.cfg file and use the value 15 for it and retest for smoother flight.

Did it .... works great, alot smoother for me! What does the 15 do, apply all 4 cores?


Also running OCCT Beta it only shows a 50% CPU usage as does CPUID as well (This is when HT is on)

It locks FSX to the 4 physical cores of the proc and my theory right now is that it also resolves thread collision problems the i7 presents since FSX is not a hyperthread application and the changes to i7 design may be making the app work a bit confused as to what is a real core and what is a virtual core.

i7 design change makes the virtual core appear like a real core. Just because HT is disabled does not mean the other part of the core is not seen by the app.. .and that may be causing FSX to spawn threads for cores that do not really exist. By the time the app figures out that the threads being spawned are not being addressed it spawns another thread to a real core and a collision occurs and a stutter may ensue.

By locking FSX to the 4 physical cores the collisions may be eliminated

[wsciutti]

Nick,

Thank you for the explanation.

One last observation which probably verifies, on my system, your theory:

I monitored the task manager while flying and the core usage is much more stable.
Instead of an EKG, cores 2,3,4 are more stable with the peaks lasting longer and the valleys not as sharp.

I think this is translates into the smooth flight I now experience.

Jack

[NickN]

ehhhh.. you cant really use that readout to make a solid estimate of what is happening.. but I get the idea

[wsciutti]

OPPS!

QUARK!QUARK! (I did get that, thanks for the rude entry to the OC club!)

Jack

[NickN]

OPPS!

QUARK!QUARK! (I did get that, thanks for the rude entry to the OC club!)

Jack

LOL!

gets'em every time  

[stevehookem]

So what's the result of this test? If I have an i7, do I enable HT or not? What's the best way to run?

[NickN]

HT disabled for FSX

affinity mask is problematical and somthin you need to work out personally for the system


HT is only useful with applications like A/V editing and engineering programs designed to make use of the virtural threads and should be enabled if you use such software

[macca22au]

Where are we now.

I overclocked the i7 940 to 3.45ghz with a BClock of 157 staying below 80c.

But performance was still unacceptable in terms of tugs and stutters.

So I enabled HT in the BIOS.  Stutters worse, and as Nick predicted temps went through the roof.

Therefore I quickly disabled HT, but then completely deleted the fsx.cfg file and allowed it to regenerate.   All I added back was the Disable Preload.

And the flying is the smoothest it has been with very high settings.

Live and learn.  All that messing with Affinity Mask, Bufferpools and TBM seemed to make things worse, and for once the default config is better.

[NickN]

[quote]Where are we now.

I overclocked the i7 940 to 3.45ghz with a BClock of 157 staying below 80c.

But performance was still unacceptable in terms of tugs and stutters.

So I enabled HT in the BIOS.

[macca22au]

I accept that, Nick, and I am eternally grateful.