Is this safe?

[a1]

I came accross this tweek if you might call it but is it safe?

For those of you running MS Flight Sim on Win XP and an Intel Hyperthreading CPU, here's a truly amazing performance booster:

After starting FS, go into task manager (CTRL_ALT_DEL)

Select Processes tab

Right click on FS9.exe, select "Set Affinity"

Disable one of the two check boxes so that FS9 only runs on one virtual CPU (I use CPU 0).

Do the same on any other running utilities (i.e. FDC, RC) and select the other virtual processor.

I see better than a doubling in frame rates. This, of course, assumes that hyperthreading is supported and enabled on your motherboard and BIOS settings.

An even better (permanent) way of constraining FS9 to run on a single virtual CPU on an HT CPU is using the Microsoft IMAGECFG utility (an older NT/2000 utility that works fine in XP -- do a google search). Command syntax (in a Command window):

IMAGECFG -a 0x1 \fs9.exe

This writes a processor affinity mask into the executable. 0x1 specifies virtual CPU 0, 0x2 specifies vCPU 1, and 0x3 uses both 0 & 1 (default). FS will always run on the specified virtual CPU(s) from that point on.

I have done the same to the other utilities I run on the machine while FS is running, only restricting them to the opposite vCPU.

I need to know how i works and how can I undo it.

Thanks

[Ashar]

Perfectly safe to do...And a real performance booster...I had that on my old machine and it gave me super FPS

[Puchu]

I love you.  :D  Works awesome.

I didn't bother changing the processor the threads run on. Just set fsx to affinity.

[justpassingthrough]

in FSX you do that in the FSX config file, not Windows. They are talking about FS9


In FSX

[JOBSCHEDULER]
AffinityMask=x

1 core (or for single core hyperthread processors)= 1
2 cores = 3
3 cores = 7
4 cores = 15

and if you use Windows XP and not Vista, make sure you have the dual core hotfix installed, even for hyperthread processors which fixes the hyperthread affinity issue for FS9 and FSX with an OS patch for graphics problems and hyperthread or dual core processor use:

http://www.microsoft.com/downloads/deta ... laylang=en

and with AMD you must use their dual core optimizer with that patch. With both AMD and Intel you must make sure the registry is edited correctly with that patch. NickN explained it here:

http://www.simviation.com/cgi-bin/yabb2 ... 57795837/0



Vista already has that fix installed

with the above patch in place you do not need to mess with affinity in FS9 anymore. It does it automatically. FSX needs the edit to the config file even after that patch is installed.

[Puchu]

Nice info. I appreciate it. I'll check it out.

Yeah, I'm on a multithreaded p4.  :-[

[Mothball]

I'm not completely sure what you guys are talking about, but could this be done in Vista also? Seems that any performance modification is a good thing. Semper Fi, Dave

[Ashar]

Semper Fi, Dave

I like that..."Always faithful"...Very cool 8-)

[Mothball]

Yes Sir, Former U.S. Marine here. I can never seem to stray too far away. Thanx for noticing. Blue sky and calm wind wishes and ... Semper Fi, Dave

[Slotback]

I don't understand. How can forcing it to run on one thread double performance? You guys sure on this?