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jabloomf1230

Hyperthreading and P3d2

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I can attest to the fact that HT does work with P3d2, although for me, there was no discernible benefit. Note my hardware setup. My PC is a hand me down from when it was solely for video editing. The computer is not designed for running P3d2 and I don't suggest anybody try to hand build such a workstation, as you will probably get much better performance with a  newer high-end single CPU mobo. My PC has 2 hexacore Xeon CPUs, for a total of 12 physical cores and 24 logical cores with HT on. With HT off, the default CFG file will allow P3d2 to run on 11 cores, as it sets an affinity mask to allow the OS and other apps to run on Core 0. If I add the AM entry to the CFG file, I can force P3d2 to use all 12 cores, but it makes no obvious difference in terms of performance.

 

If I turn on HT in the mobo CMOS setup, P3d2 runs on every even numbered core, which is exactly equivalent to its use of 12 cores with HT off. If I put in an affinity mask of:

[JOBSCHEDULER]
AffinityMask=16777215

P3d2 uses all 24 logical cores fairly evenly. However, it doesn't improve performance one bit. Then again, I don't have any stuttering with either HT on or HT off and I have the P3d2 sliders set to give me around 30 fps.

 

I don't claim that this post constitutes anything more than a casual observation, but I thought that some people might be interested.

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P3d2 uses all 24 logical cores fairly evenly. However, it doesn't improve performance one bit. Then again, I don't have any stuttering with either HT on or HT off and I have the P3d2 sliders set to give me around 30 fps.

 

Same here, except for 12 logical cores ...

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LM claims that they have a default AM that prevents P3d2 from using core 0, so that the OS and other apps may use core 0 exclusively. Core 0 is getting used, just not by P3d2. Run Process Explorer and check the AM for P3d2. It's very possible that it doesn't work the same for everybody, depending on how many physical cores are present and whether HT is on or off.

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I don't have the tweak in my config and P3D detects all 12 cores.

 

I have the same processor and flight just a core operating at 100% the rest rests almost

l0fg.jpg

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I thought I read from one of the devs is that you can leave hyperthreading on and they have implemented a more intelligent core scheduling. By default not using core zero and not using the hyper threaded cores. On my system this seems to be the case ( I7 six core 12 with hyperthreading) core zero and the hyperthreaded ones remain unused. BUT some people with AMD systems were having to use an AM because the program isn't detecting their cores properly. I would check what bears out on your specific system prior to just automatically adding this tweak ala FSX. You may not even need it at all if it works fine. 

 

As far as the OP's observations I think maybe that there is not enough work to pass off to that monster setup :) You can only really offload so much work from the main thread before it becomes more overhead than help.

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l0fg.jpg

Weird, I have HT on which you seem to have as well. I do know that core 0 is being used for the OS and everything else is being used by P3d.

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The net result of all this is to not worry about whether HT is on or off and to not mess with the affinity mask.

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The net result of all this is to not worry about whether HT is on or off and to not mess with the affinity mask.

Completely agree.

 

I have spent hours trying every combination of AF on my system. I have Hyperthreading ON I've not just tried each setting for a few minuets but used Each setting for several days.

 

With any combination of AF 252/255 or 84/85 (just because), I ALWAYS get a better result with a default config. I.E. one without any AF set.

 

I guess every system is different!

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