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Guest Ken_Salter

Hyper Threading and FS9

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Hi,I have a Pentim 4 3.02Ghz, and was wondering if using the hyper threading was of any benefit to FS9, or is it best to disable it ?Regards,Adam. :-shy

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I have the same system and was wondering about that, too.If the answer is "disable", how do you do that? I cannot find any instructions about disabling hyper threading.Thanks for the question.

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Adam, if I remember correctly, it was stated during the development phase of FS2k4 that it supports multiple processors, whether they be physical (dual CPU system) or logical (hyperthreading or any variant thereof) so I would think that enabling HT would provide more performance than disabling it. Only one way to find out though, setup a situation and record some frame rates with HT on, and repeat the same situation with HT off. Obviously the more situations you setup and the more times you repeat them, the more reliable your findings will be.And to the gentleman who posted below you, one should be able to enable/disable HT within their mobo's bios. hope this helps,Max Cowgill

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FS9 isn't multithreaded, meaning HT and dual CPU's wont help it at all. My friend has a dual Athlon MP system and he says it only uses 1 CPU, meaning its single-threaded. Its too bad its not multithreaded, because people with dual CPU systems would rock at running FS9 LOL. the Pentium 4 systems would see a marginal increase, but not a whole lot. But since its single-threaded, P4's wont see any performance gain/loss by turning HT on or off.

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Zack, this is contradictory to the information MS has put out regarding the use of multiple processors (physical/logical) and FS9. Do you have any other evidence to support your statement, other than the anecdotal evidence you've provided? I'm not saying you're lying, it's just odd that MS would claim support for dual processors/HT and the opposite would prove true.-Max Cowgill

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FS9 IS multithreaded. If your friend's dual athlon only shows one CPU running then its not configured properly. What OS is he using? My HT system clearly shows "both" CPU's heavily engaged with FS running.Even if FS WASN"T multithreaded itself, the dual CPU would still be much faster as the OS would offload background tasks to the 2nd processor. CPU load balancing is handled by the OS - not the application. A program that explicitly spins off different threads during execution simply allows the OS to do the job more efficiently. The app has no direct control over which CPU will run which thread.Adam, I can't imagine any reason beyond pure diagnostic testing that you would ever want to disable Hyperthreading.BTW. I assume everyone knows that you must be running Windows 2000 or XP to take advantage of Hyperthreading. Win9x and ME don't support multiple processors.

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I assume everyone knows that you must be running Windows>2000 or XP to take advantage of Hyperthreading. Win9x and ME>don't support multiple processors. Unfortunately Windows 2000 does NOT support HT correctly--it does however support multiple processors. HT is the ONLY reason I would move from Win2K Pro to XP.Noel

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I never tought I would say this but...As it happens, I just had a strange experience with this very subject.Contrary to what MS say, I'm don't think FS9 does benefit from HT. I too thought that it would, I believe at one time they said the weather engine would run as a seperate process on HT, but I've never seen CPU usage for FS9 rise above 50% on my HT enabled P4C WinXP system-and I have tested with all sorts of benchmarks to make sure HT was set up correctly in the first place. Although FS9 may not benefit directly from HT, I figured that HT would still help performance by handling background tasks and such, so I did not think of disabling it before.Yesterday, RealityXP released the FS2004 version of their GPS530XP, and after installing it, I experienced big FPS problems. In the RXP forum, Jean-Luc suggested disabling HT...and the difference is astounding! FS9 is running MUCH smoother and faster than it ever did, and I'm now convinced that FS9 may be having problems dealing with HT, at least on my system; point is, disabling it didn't help just with the RXP stuff, but improved FS performance overall, with a lot less disk access. Maybe adding more memory might have helped too, but I cannot afford that right now.It's early days yet, and we're just starting to find our way towards better performance, and workarounds and tweaks may improve the situation later on, but for now, HT is off on my comp.P4c 2.6 @ 3.2, 512Mb DDR PC3500, Radeon 9700 Pro, SB Audigy2, Win XP

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Yes FS is multithreaded but what I want to know is what is happenning in a dual logical processors. I don't have an HT in a normal CPU FS9 presents 13 threads (with PMDG loaded) but only one as all the processing the others just sit there doing almost nothing. I'm using MS Spy++ to see the threads don't know if there is any other tool to investigate but I'm very interested to see what happens specially during a weather update.Jos

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Hi,If your OS is Windows XP(Home or Pro), including service pack 1:There is a problem with hyper threading.SP1 causes a dropdown in performance.Have a look in Microsoft's knowlegde base nr.815227Here's the link: http://support.microsoft.com/default.aspx?...kb;en-us;815227SP2 will fix this problem, but as you may know this will take some time......!!Following the above link gives you the possibility to ask for this fix at once!Regards Johan

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-"but only one as all the processing the others just sit there doing almost nothing.-" Have you noticed any difference between removing the cd after Fsim starts vs. leaving the cd in the entire time ?Kurt M

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You can disable hyper threading in the bios, but I would never advise anyone to do that. When running FS9, I never see it go beyond 50% on both processor instances. However, using UD to take use of the other half of the processing power results in a noticable slowdown. UD had never caused any slowdown on a non hyper threading processor. It seems there are some issues with task preemption once there is processor power available for other tasks, so while 50% of the processor is available when running FS9, I got a noticable improvement when turning off all background tasks such as UD, asus probe en mouse software.

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Seems though that many benefit from disabling it?!Also, don't expect much from Windows XP Home:The processor limits which result from this licensing model for 32-bit versions of the Windows Server 2003 family and Windows XP are shown in Table 2.Windows Version Maximum Physical Processor Limit Maximum Logical Processor LimitWindows XP Home Edition 1 2Windows XP Professional 2 4Windows Server 2003, Standard Edition 4 8Windows Server 2003, Enterprise Edition 8 16Windows Server 2003, Datacenter Edition 32 32Table 2. Processor Limits for 32-bit Versions of the Windows Server 2003 family and Windows XPAlso note there are 3 topics covered with HT:As a result of the HT processor identification support, the following HT-aware features are included in Windows XP and the Windows Server 2003 family.

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Please correct me if I'm wrong, but:1) FS9 is multi-threaded2) At least on Win XP Pro, there is support for multi-processors (real or "simulated")3) The OS is responsible for assigning CPUs to threads if the program itself does not careTherefore:How could FS9 not benefit from any multi-cpu configuration?http://saltydogfly2.avsim.net/images/avsim_sig.jpg"We are the music makers, and we are the dreamers of dreams."

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