A Frame-Time Analysis of P3D v3 -- Effects of CPU Affinity, Frame Lock, and HT

[SteveW 1,792]

Hi Dom,

 

Usually AM=14 is recommended for a 4 core HT disabled CPU and the sim avoids core zero.

 

Unless you are going for maximum overclock, enable HT and use AM=85. If you want to run HT disabled use AM=0.

 

If you run external addons, perhaps a weather engine for example, and you want to avoid core zero, then try AM=116 (HT=On), or AM=14 (HT=Off).

 

If your external addon can be made to run with an AM then make that avoid core zero and use AM=85 (HT=On) or AM=0 (HT=Off) for the sim.

 

If you are a maximum overclocker, the post I made just above may help.

[Domobaby 1]

Wow, all sorts of options. 

 

Ok I will check and see what my HT setting is when I get back and try one of these.

 

Thanks Steve.

 

Dom

[SteveW 1,792]

You're welcome Dom!

 

We've got better understanding of how the sims work across multicore, and better means of testing performance to qualify it these days. But Affinity masks affect heat and PC smoothness far more than sim fps, so it's a mistake to look at just fps. It's also possible for the fps to appear high, and yet the sim perform poorly. So these suggestions should be carefully set, and given time across various scenarios.

 

All the best.

[G-YMML1 582]

Steve,

 

Just to summarize...if I'm using a average OC (4.6-4.7 with 1.35/1.37 voltage on I7-6700k), does it mean that I have to have HT=OFF in BIOS and AF set to 14 in P3D.cfg? I'm using ASN, PATC as external addons,

 

Thanks

Dmitriy

[SteveW 1,792]

Steve,

 

Just to summarize...if I'm using a average OC (4.6-4.7 with 1.35/1.37 voltage on I7-6700k), does it mean that I have to have HT=OFF in BIOS and AF set to 14 in P3D.cfg? I'm using ASN, PATC as external addons,

 

Thanks

Dmitriy

This is a simple use of 3 cores ignoring HT (hatemethreading), and will work fine. The difference in heat with HT enabled and 116, for 3 core operation is very close but with an overclock near the limit who knows without testing. HT does more work, more work produces more heat, but not the sort of work that will increase fps of the sim. If you want to use 2 cores and can go even cooler, whether with HT disabled AM=6=(0110) or HT enabled AM=52=(00,11,10,00) or AM=60=(00,11,11,00). Overall the PC is more zesty with HT enabled, but could make enough of a heat increase to trip up the overclock.

 

We can come down on core use, and heat, by reducing the number of cores used with an appropriate mask. We can turn off HT to go a little cooler, but not by much. Mostly, overheating is caused by an inappropriate AM, irrespective of HT operation. The fact is, turning off HT is small by comparison to using less cores to go cooler, but either will produce a lumpier sim for only a few more MHz OC. In my opinion it is unnecessary to go for the last few MHz and gain maybe one or two fps. Especially with these simulators, they are not twitch games and work differently as simulations.

[funkyj4ever 2]

I have an i5 4690K @ 4.4ghz and a gtx 670(think that this is my bottleneck)

What can i do to have beter perfomance? I already have 30frames locked in sim and have most options set to medium. 

[SteveW 1,792]

The best you can do with 4 core no HT is run without an AM, and keep addons off core zero if you can or try an AM of 14. You're probably OK with 30 locked, but maybe can try 30 limiter (or 29) in NI, and set vsync on and triple buffer on and unlimited fps in P3D. P3D frame rate can be improved by reducing shadow cascade values in the cfg [GRAPHICS] section to no more than 6, and with the GTX670 class GPU try reducing tessellation beyond the slider full left:

 

Tessellation set low in the Display Settings is 60, but can be set around 50-20 for better performance, even 20 should be better than no Tessellation at all.

[GRAPHICS]

TESSELLATION=1

[TERRAIN]

TESSELLATION_FACTOR=25 (50% or below for performance, above for quality.)

 

choose a texture multiplier to go with your class of scenery

[Display]

TEXTURE_BANDWIDTH_MULT=180 (Smoother texture handling with medium+ autogen.)

TEXTURE_BANDWIDTH_MULT=10 (Smoother frame rate with very low or no autogen.)

and use TEXTURE_FILTERING=8 rather than 16

 

Use only 4xMSAA in P3D for AA, with most planes that's OK e.g. B58, but don't use NI unless you use a certain type of plane model, e.g. A36, then NI would be required to set 4xSGSS to go with the 4xMSAA to get anti-aliasing on those and similar models. There's a possibility of scenery with the same AA issue, but SGSS with NI is a frame rate eater..

[Mickeyj 35]

Hi there,

 

just an observation and experience i made in the last couple days fiddling around with this AM stuff. First of all thank you Steve and Rob for their patience, recommendations and tips. 

 

So i have an i7 5820k HT=ON  + 980 SLI (4SGSS via NI) system. In now run AM=340 which gives me a good result in most cases. But switching on core 11 (i think it is the LP of core 10) within Process Lasso reduces a little bit more the stutters when running TrackIR+EZCA. I already took them and ASN (sometimes i run ASN via network) off of core 2.

 

I set TEXTURE_BANDWIDTH_MULT=160, FFTF=0.01, TextureMaxLoad=27 within the cfg. Performance FPS Smoothness A OK

[warbirds 555]

"P3D frame rate can be improved by reducing shadow cascade values in the cfg [GRAPHICS] section to no more than 6,"

 

Which one, there are four.

[reecemj 144]

 

 

P3D frame rate can be improved by reducing shadow cascade values in the cfg [GRAPHICS] section to no more than 6

 

Steve what does this do to the shadows? Am using it and I don't see any differents in shadow quality but may have pickup a few fps. 

[funkyj4ever 2]

The best you can do with 4 core no HT is run without an AM, and keep addons off core zero if you can or try an AM of 14. You're probably OK with 30 locked, but maybe can try 30 limiter (or 29) in NI, and set vsync on and triple buffer on and unlimited fps in P3D. P3D frame rate can be improved by reducing shadow cascade values in the cfg [GRAPHICS] section to no more than 6, and with the GTX670 class GPU try reducing tessellation beyond the slider full left:

 

Tessellation set low in the Display Settings is 60, but can be set around 50-20 for better performance, even 20 should be better than no Tessellation at all.

[GRAPHICS]

TESSELLATION=1

[TERRAIN]

TESSELLATION_FACTOR=25 (50% or below for performance, above for quality.)

 

choose a texture multiplier to go with your class of scenery

[Display]

TEXTURE_BANDWIDTH_MULT=180 (Smoother texture handling with medium+ autogen.)

TEXTURE_BANDWIDTH_MULT=10 (Smoother frame rate with very low or no autogen.)

and use TEXTURE_FILTERING=8 rather than 16

 

Use only 4xMSAA in P3D for AA, with most planes that's OK e.g. B58, but don't use NI unless you use a certain type of plane model, e.g. A36, then NI would be required to set 4xSGSS to go with the 4xMSAA to get anti-aliasing on those and similar models. There's a possibility of scenery with the same AA issue, but SGSS with NI is a frame rate eater..

Thanks

 

do you now what this is? 

GROUND_SHADOW_TEXTURE_SIZE=2048

 

and this is correct? 

SHADOW_NUM_CASCADES_LOW=4

SHADOW_NUM_CASCADES_MID=5

SHADOW_NUM_CASCADES_HIGH=5

SHADOW_NUM_CASCADES_ULTRA=6

 

and what about fftf0.1

[Mickeyj 35]

 

Thanks

 

do you now what this is? 

GROUND_SHADOW_TEXTURE_SIZE=2048

 

and what about fftf0.1

 

 

GROUND_SHADOW_TEXTURE_SIZE=2048 is the texture resolution of the shadow that is painted on the scenery. Max size is 4096 lowest size is 256.Stay away from 4096 its pretty heavy on the frames.

 

Unfortunately i cant say anything about the cascades. Please refer to LM. But maybe Steve or Rob would know.

[Cruachan 705]

Hi,

 

Please feel free to shoot me down in flames if what I am about to say is incorrect or unrepresentative of what is really happening out there.

 

A great deal of very helpful advice is being offered with the very best of intentions. Sadly, the three variables mostly being omitted from these discussions is, in each case, the specific in-sim settings, the chosen vehicle and the identity, quality and density of the scenery where you fly. Time and time again we read of the happy experiences of simmers who have found their ideal settings with very little in the way of qualification. Others reading these posts only become frustrated as their experience following the application of various settings often differs and performance cannot be maintained in any consistent sense.

 

After much testing, I have come to accept that there is no collection of settings in or out of the sim which will ensure smooth flight everywhere. In the end I have to accept a compromise knowing that certain situations coupled with my chosen vehicle and unchanging settings will guarantee smooth flight whereas others will not. This may seem like stating the obvious. However I feel fairly certain that most of you will know already that this is correct.

 

I have been advocating the use of G-Sync (with G-Sync enabled, high refresh rate monitors receiving output from compatible NVIDIA GPUs) while qualifying this statement by saying that it only really works effectively while frame rates are sustained at relatively high levels - over 30 and preferably greater than 40fps. In high performance gaming it has no equal and the results are very impressive and consistent with lag-free super smooth screen updating.

 

In Prepar3D v3.1 I had abandoned the use of Affinity Masks, VSync and Triple buffering believing that G-Sync was the answer that allowed me finally to abandon all that wearisome tweaking. The reality is now proving to be rather different.

 

For example:

 

Scenery Complexity: Extremely Dense

Autogen Vegetation Density: Extremely Dense (perhaps contrary to what one might expect I find that the higher autogen veg. density setting gives me smoother performance - this might be different on other specced rigs)

Autogen building Density: Dense (higher settings can induce stutters and intermittent graphic spiking artefacts)

 

Two situations: (1) Eglin AFB (KVPS) and (2) A few miles south of Lancaster ((KLNS) which is SE of KJFK.

 

Scenario: Tree skimming @ 200ft AGL, 140knots, frequent banking and turning intermingled with extended periods of straight line flying.

Vehicle: Alabeo Extra 300s Red

Monitor refresh: 120Hz, G-Sync DISABLED

VSync and Triple buffering ENABLED in sim.

Frame rate: Unlimited (has always been my preferred setting for smooth performance)

Frame rates monitored with MSI Afterburner.

ORBX: FTX Global selected.

Fair Weather - REX4 TD Soft Clouds

NVIDIA Inspector: SGSSAAx4

Prepar3D: MSAAx4

 

(1) Sim paused: 70fps, Unpaused and Flying: 58fps (Stutter-free)

(2) Sim paused: 60fps, Unpaused and Flying: 58fps (Stutter-free)

 

So, for (1) and (2) very similar demands were being imposed on the hardware (details below post).

 

Now, I try flying with G-Sync ENABLED and intermittent micro-stutters appear in (2) while (1) remains stutter-free for the most part.

 

This may not mean very much, but does serve as an example where performance in relatively similar situations can be different and this observation can, potentially, lead to further head scratching and unwelcome tweaking. As you see, I have a CPU with 8 physical cores (16 LPs with HT ON). I have battled with numerous Affinity Mask values yet none gave me that consistent smooth performance. Indeed, as part of my over-clocking I decided to disable HT in the BIOS and, coincidentally, found that disabling G-Sync along with the re-enabling of VSync and Triple Buffering is now delivering smooth performance in a much wider range of situations and frame rates.

 

As they say, just my two pence worth. Like everything else involving this simulator and the resident host hardware, YMMV. However, for me the message remains the same: without the provision of specific qualifying details, statements about smooth stutter-free running are largely, dare I say it, unhelpful and really only apply to that poster's experience based on the numerous variables as applied to his/her setup.

 

Mike

[SteveW 1,792]

"P3D frame rate can be improved by reducing shadow cascade values in the cfg [GRAPHICS] section to no more than 6,"

 

Which one, there are four.

"by reducing shadow cascade values" - i.e. all or one of them, there are 4 and each one corresponds to one of the 4 shadow quality settings.

 

By reducing to 6 or below, we increase fps and decrease VAS used.

 

 

do you now what this is? 

GROUND_SHADOW_TEXTURE_SIZE=2048

We can increase the quality of shadows without such an fps hit as cascade count, by increasing the GROUND_SHADOW_TEXTURE_SIZE to 4096, but memory is increased back slightly, and there is a slight (minor) increase in time to pull in objects.

[SteveW 1,792]

Steve what does this do to the shadows? Am using it and I don't see any differents in shadow quality but may have pickup a few fps.

Yes you get more fps that's for sure, but you may not notice the changes in quality, because it depends on the angle and position of viewing the shadows. With less cascades there will be a harder edge to the shadows. Shadows need slight improvement in P3D, but currently it's a compromise of quality for speed.