2 hours ago, Ray Proudfoot said:

All 8 of my virtual cores are working so why would I change that?

That´s exactly what costs performance and raises VAS consumption. Sounds really weird, I know ;-)

Because you asked me: I use UT2 for AI traffic and customized it´s aircraft with different Freeware AI models and repaints (which I downsize to 1024k if they were bigger than that). But that´s not the point, let´s get back to the Hyperthreading topic.

You earlier said that you use Affinitymask 255 on a i7 with HT what means you have 8 virtual cores. That combination is not optimal if not to say wrong.
The reason why is explained in this old (but excellent) thread in another forum where steveW explains really well how hyperthreading works in combination with P3D (or FSX) and I do 100% agree with what he says => http://www.codelegend.com/forums/viewtopic.php?f=2&t=532

If you really insist on using HT you have to use a convenient value for your affinitymask! AM 255 for a i7 with HT on is not convenient. Otherwise you will get higher VAS consumption and slightly worse performance. If I for example enable HT on my system (which is also driven by a i7 quadcore) without using a suitable affinitymask value I got decreased FPS by 10-15% and serious trouble with raised VAS usage by 500MB or more, especially in autogen-dense areas. I spent dozens of hours testing different sim configurations which also included lots of testing with HT on/off and several affinity mask values. If I use HT on my rig I do that in combination with AM values 116, 84 or 85. I can´t do more than recommend you to test your P3D with these AM values if you have HT switched on. If you want to test with HT off: Don´t do that with your current AM setting of 255! With disabled HT that would be even worse.

Meanwhile I also had a look at Robs P3D guide and I have to say it´s brilliant. The only thing I miss a little is that in my opinion Hyperthreading and Affinitymask settings don´t get the attention that these topics actually deserve considering that the usage of the right combination is one of the most essential aspects if you want to get a smooth running sim.

Hi Schollerknei,

I'm enroute Oslo-London at present but when I've landed I will certainly research what you have provided, thnaks. I never thought AF did much but obviously it does. If the VAS savings are that much why isn't it recommended procedure on LM's site to change it? Strange.

Reported VAS savings by serveral users on several forums differ very much somewhere between 0 and 500MB. When I use a wrong AM setting with enabled HT my system is definitely more on the extreme side ;-)
I´m curious if it works out for you...

Happy landings!

I searched around in the BIOS for HT but couldn't find it. After googling my mobo turns out it's in the overclocking section.

To save this old bugger from having to read large amounts of stuff on best settings can someone give me an AM number that will improve things for me please? Intel 4770K o/c to 4.4.

After turning HT off in the BIOS do I edit P3D.cfg and change HT and AF settings there or somewhere else?

If you want to test P3D with disabled Hyperthreading simply delete your AffinityMask entry from your cfg.
To test with HT enabled set AffinityMask to 84, 85 or 116 for example. Which AM works best for you is mainly a matter of testing although all three of them should deliver better results with HT on than your current setting of 255. For a detailed describtion how these different AM values work just have a closer look at that link I posted before.

You don´t need to change anything else than that HT on/off switch in you BIOS and the according AM value in the p3d.cfg.

With HT OFF: Remove the Jobscheduler and AffinityMask entry from your cfg.

With HT ON: Try values 84, 85 or 116 for AffinityMask

Thanks Schlotterknie. Perfect. I'll post when I've done some testing. It seems safer to comment out the AM entry in P3D.CFG rather than mess around in the BIOS.

Just to be sure... :
If you comment out your AM entry HT has to switched OFF.
If you want to test with different AM settings HT as to be switched on.

Don´t be afraid to flip the hyperthreading-switch in your BIOS. That won´t harm your hardware. I can´t anymore count how often I changed that BIOS-setting the last one or two years ;-)

1 hour ago, Schlotterknie said:

With HT OFF: Remove the Jobscheduler and AffinityMask entry from your cfg.

Hi Ray,

No need to remove the entry, just comment out the "AffinityMask" line by adding a couple of forward slashes at the beginning of the line.

However, as I hinted at before, if you are happy with your performance now then why rock the boat! Adding an AffinityMask value will only 'improve' performance by avoiding contention on the main P3D thread, assuming you are using .exe Addons that may try to use this core. Are you using ActiveSky? If so, are you still getting good performance without stuttering, micro or otherwise. If the answer is yes then leave things as they are. I'm not certain, but I'm guessing that ActiveSky has its own AffinityMask and is setup to keep away from the main P3D thread which is usually on core 1. 

Prepar3D has been shown to perform best using 4 cores - the main thread on core 1 and a secondary, less active thread on core 2. The other 2 cores are occupied with loading textures. With Hyperthreading on for a quad cored CPU you have 4 additional virtual cores to work with and these can be used to run resource hungry Addons that might impede the performance of the sim. The Windows Jobscheduler takes care of that...unless you assign an Affinity Mask to each Addon by using batch files...and that's another story! When you specify an Affinity Mask, all you are doing is telling the Jobscheduler which cores you want allocated exclusively to the running of Prepar3D while the remaining cores can be used by the various Addons running alongside without risk of sharing/compromising the main sim thread activity.

Turning off CPU Hyperthreading in the System BIOS for a quad cored processor will restrict your options and could hamper overall performance if you confine P3D to running on only 3 cores with the intention of reserving the remaining core for any Addons. My i-7 5960X has 8 Physical cores to play with so there is greater flexibility without any need to enable the remaining 8 virtual cores.

Regards,

Mike

My system ( 5820 / 6 core ) runs smoother with HT enabled + AM 340

Mike,

My main aim is to increase available VAS rather than boost frame rates which are fine. As well as P3D I also run the following :-

AS16, ASCA and EFB Data Provider. I can't imagine any of those are memory or CPU hungry.

Does that help? The conflicting advice - whilst welcome - is confusing.

1 hour ago, Ray Proudfoot said:

Mike,

My main aim is to increase available VAS rather than boost frame rates which are fine. As well as P3D I also run the following :-

AS16, ASCA and EFB Data Provider. I can't imagine any of those are memory or CPU hungry.

Does that help? The conflicting advice - whilst welcome - is confusing.

Hi Ray,

Yes, you are right and this thread has drifted off topic somewhat. My advice, for what it's worth, is to stick with what you have meantime and concentrate on managing the VAS issue by adjusting settings within the sim. Use Rob's guide as your reference.

By all means experiment with HT On/Off and Affinity Mask settings. If nothing else you will become more familiar with the way P3D performs under different conditions. While we can offer general advice and guidance, in the end how your sim delivers will depend on the local software/hardware environment. By the sounds of it, apart from the VAS issue, you seem pretty happy with the way things are so perhaps there is little to justify complicating things needlessly. With your i7-4770K I would leave HT ON and let the Windows Jobscheduler handle the rest.

BTW, I note your GPU has changed itself again in your sig 😉 

Regards,

Mike

1 hour ago, GSalden said:

My system ( 5820 / 6 core ) runs smoother with HT enabled + AM 340

That´s interesting. How did you get to an AM value of 340 for your 6 core CPU?
Im asking because AM 340 is actually an invalid value for that CPU model. AM 340 in binary equals 01 01 01 01 00. That 5 pairs mean you´re adressing only 5 cores instead of all 6.
=> Nr 1, 2, 3 and 4 with one thread, nr 5 with none and core nr 6 is missing completely. I don´t know how P3D handles AM values that doesn´t suit to the number of available cores/threads.

 

1 hour ago, Ray Proudfoot said:

Mike,

My main aim is to increase available VAS rather than boost frame rates which are fine. As well as P3D I also run the following :-

AS16, ASCA and EFB Data Provider. I can't imagine any of those are memory or CPU hungry.

Does that help? The conflicting advice - whilst welcome - is confusing.

A suitable combination of HT on/off and your AM setting will most likely lower VAS consumption significantly. You can see a potential gain in FPS as a positive side effect.

30 minutes ago, Schlotterknie said:

That´s interesting. How did you get to an AM value of 340 for your 6 core CPU?
Im asking because AM 340 is actually an invalid value for that CPU model. AM 340 in binary equals 01 01 01 01 00. That 5 pairs mean you´re adressing only 5 cores instead of all 6.

Actually, on a 6-cored CPU I think the AffinityMask 340 would appear as 00,01,01,01,01,00 leaving 2 Physical cores (4 unmasked virtual cores) free for allocation by the Windows Jobscheduler to Addons. This is in addition to the 4 unmasked virtual cores on each of the other 4 physical cores.

Reading from right to left you have the binary representation for cores 11,10,9,8,7,6,5,4,3,2,1,0. With AM=340 Prepar3D will use cores 2,4,6 and 8.

Mike

17 minutes ago, Cruachan said:

With your i7-4770K I would leave HT ON and let the Windows Jobscheduler handle the rest.

That´s exactly the root of the problem we´re talking about: That 'automatic' job scheduling just doesn´t work as it should.

The problem isn´t the Windows jobscheduler. That one simply has to share CPU load on all available/free cores. The problem is the P3D jobscheduler as it doesn´t consider how many cores/threads are available on the system it´s running on and adapt a proper AffinityMask for it´s own needs, although that information would be easily accessible just by asking the Windows API. I guess this lack of self-configuration is one of the main reasons why a lot of i7 users have problems with increased VAS usage and OOM crashes.

2 minutes ago, Cruachan said:

Actually, on a 6-cored CPU I think the AffinityMask 340 would appear as 00,01,01,01,01,00 leaving 2 Physical cores (4 unmasked virtual cores) free for allocation by the Windows Jobscheduler to Addons. This is in addition to the 4 unmasked virtual cores on each of the other 4 physical cores.

Mike

Hmmm... ok, two more leading zeros sound reasonable. So at least one dubiety has gone now ;-)