30fps unobtainable but core 0 is not at 100%

[simfan1983 185]

Just now, Ray Proudfoot said:

Chillblast said in another email that reverting to the default BIOS setting would restore core 1 to 5.0Ghz as the chart shows. No tweaking required. But cores 4-6 would run slower.

I don’t think it’s going to make that much difference to be honest.

Maybe it will but when you are running multiple tasks it will probably throttle back. If you save your current BIOS settings and then use default you could give it a try. My 8700k never did the advertised turbo boost speed on a single core when running multi-threaded applications.

[Bryn 72]

I noticed this problem when I directly set the affinity for the prepar3d.exe to unload CPU 0 and then reload back on to CPU 0 (and all cores). CPU usage was well below 100% after that (like yours), but FPS still stayed around 27 to 28. GPU was not limiting either- that was bumping along at around 45%.

If the CPU is not limiting fps (well within 100%) and the GPU is not limiting fps, what else could be? 

Not throttling - it would be 100% CPU but at a slower speed.

 

[Ray Proudfoot 8,947]

12 minutes ago, simfan1983 said:

Maybe it will but when you are running multiple tasks it will probably throttle back. If you save your current BIOS settings and then use default you could give it a try. My 8700k never did the advertised turbo boost speed on a single core when running multi-threaded applications.

I use SimStarterNG to launch other executables and each is assigned an AM setting. Nothing other than P3D uses core0.

I might try swapping but to be honest in today’s scenario there were too many other factors adding to the complex situation. EGLL is less than 30 miles away and all the Ai there do have a bearing on Gatwick. Plus lousy weather. 

[Ray Proudfoot 8,947]

1 minute ago, Rob_Ainscough said:

Is Triple Buffering enabled?

EA on?  If so EA on and Volumetric Clouds on?

Cheers, Rob.

Yes.

No EA. Tried it a few times and really dislike it as HDR is also enabled and I dislike that too.

Let’s see how 3 cloud layers work. Setting ASCA to minimum quality textures didn’t do much.

If others have UK2000 Gatwick do you find it’s processor heavy? Unusual for a medium sized airport.

@Bryn, I only use cores 0, 2, 4, 6, 8 and 10 for P3D. Assigning all just overloads core 0.

[Bryn 72]

10 minutes ago, Ray Proudfoot said:

 

@Bryn, I only use cores 0, 2, 4, 6, 8 and 10 for P3D. Assigning all just overloads core 0.

Sure, but it seems a common factor between our experiences is the manual assignment of the cores (rather than the cores used).

[Ray Proudfoot 8,947]

6 minutes ago, Bryn said:

Sure, but it seems a common factor between our experiences is the manual assignment of the cores (rather than the cores used).

It’s the first time I’ve encountered this situation. I believe it’s a one-off. My AM setting is not assigned manually. I use software to set it.

[Ray Proudfoot 8,947]

I've flown circuits around EGKK with various weather scenarios having established that Ai traffic is not an issue. Neither is ASP3D / ASCA cloud texture settings or cloud layers at 5 having a significant impact.

For the last test I closed ASP3D/ASCA and set Cold Fronts in P3D Weather which has a reasonable amount of cloud but nothing that is detrimental to peformance.

On the downwind and base legs cpu0 was below 100% and fps was 30. Turning onto final fps still remained at 30. But at 4nm out the fps dropped to the mid 20s and stayed around that right up to the landing.

I can only assume there is something in the design of UK2000 Gatwick causing the issue. As that version is 4 years old and with no sign of another P3D version it's something I'm going to have to live with. 25fps on approach is hardly a major problem.

The original reported problem has never reoccured so I'm putting it down to an anomaly.

[Peter Webber 339]

13 minutes ago, Rob_Ainscough said:

I stopped using AM a long time ago for P3D, just disabled HT in BIOS which allows for less heat and higher CPU frequency.

Sounds like something is not working correctly with your AM, have you tried to disable HT and just run 6 real cores? 

Win10/11 should be left alone to manage tasks.  I think you've added more complexity than is really needed with P3D V5.x.  With the introduction of DX12 in P3D V5.x, can't really equate P3D V4.x configurations to P3D V5.x.

Cheers, Rob.

Agree. I don't make any modifications, and also leave settings as default in nvidia control panel.

[Ray Proudfoot 8,947]

@Rob_Ainscough, there’s plenty of valid arguments for and against AM. V5 has been tweaked several times by LM and who’s to say they won’t do further tweaks. The trouble is they don’t explain via a readme what has changed. We’re left guessing.

Ive had this computer for over 3 years and overall I’m happy with performance. I have assigned an AM that uses cores 0 2 4 6 8 and 10. @SteveW has confirmed there’s no problem doing that. I’ve tried assigning all cores but performance was worse but with Hyperthreading still enabled.

I wish someone who has UK2000 Gatwick could try a circuit and report back.

Have you noticed that many default airport buildings do not appear until Scenery Density is set to Very Dense. In v4 Normal was sufficient. I’ve reported it to LM but despite a helper there confirmed it no acknowledgment was forthcoming. Disappointing. ☹️

[Bryn 72]

2 hours ago, Rob_Ainscough said:

Sounds like something is not working correctly with your AM, have you tried to disable HT and just run 6 real cores? 

Win10/11 should be left alone to manage tasks. 

Just to chip in again - I do the same mostly. However, sometimes when core zero is stuck at 100% and fps appear degraded, I sometimes find that I can get my fps to bump back up to normal by offloading core zero and then onloading back on to all cores a few seconds later.

Now I think about it, it could be because the constant 100% on core zero is causing power or thermal throttling, lowering fps, and the offload and onload gets the CPU out of that state. I guess I should check that out next time...

Now I think about it a bit more... perhaps throttling is a reason some people see poorer performance when they have all their cores running with HT, particularly if they're oced. The AM reduces power load and/or heat, and so reduces any power throttling or thermal throttling that might have been taking place, and the sweet spot ends up being fewer cores but running faster.

 

Of course, that doesn't explain why fps might get stuck below 30 with GPU and CPU basically cruising along at about 50%.

Edited July 26, 2021 by Bryn

[Ray Proudfoot 8,947]

1 hour ago, Bryn said:

Now I think about it a bit more... perhaps throttling is a reason some people see poorer performance when they have all their cores running with HT, particularly if they're oced.

But not all the VPs were throttled. 0 was but 1 was just idling. Scenery loading is done by 2, 6 and 10. I assume Windows arranges that.

Ill give consideration to trying with HT off.

Of course, that doesn't explain why fps might get stuck below 30 with GPU and CPU basically cruising along at about 50%.

That situation has not occurred again in all my tests today. As I said earlier, that was just an anomaly.

[neilhewitt 493]

Odd things do sometimes happen. Just yesterday, my FPS suddenly dropped between sim sessions from 30 to 5 in the exact same scenario. I worked out it was due to undocked panels, each one was halving my FPS, but I had been running at 30fps with all those panels undocked literally 10 minutes before. I tried all the usual techniques but nothing worked. Then I went into my Nvidia settings and the driver was set to 'use the advanced 3D settings', presumably because I had fiddled with some settings (and then reverted them to stock), and when I changed that back to 'use the 3D application settings', FPS went back to normal. But all the fiddling had happened a couple of days before and I had flown the sim at 30fps since then... meh. Sometimes you just take the win.

On the whole HT thing... hyperthreading works great for some kinds of loads, but at the end of the day a logical processor is just that - not actually real. Both LPs share one actual physical core, and that core can only really execute one instruction at a time; it's the stuff around the instruction execution that can be done on each LP separately to speed the whole thing up. I have no idea if P3D is the kind of load that works well on HT or not, but I do know that I get better performance generally with HT off. YM, as always, MV.

[Ray Proudfoot 8,947]

@neilhewitt and @Rob_Ainscough. You seem to know your onions. What’s the official advice from LM? Surely they know what works best for their code?

HT on or off?

[kevinfirth 1,393]

4 hours ago, Ray Proudfoot said:

@neilhewitt and @Rob_Ainscough. You seem to know your onions. What’s the official advice from LM? Surely they know what works best for their code?

HT on or off?

I'd say it depends on your CPU. If you have a four core or 6, definitely HT on to maximize terrain loading threads and have cores for other apps.  Getting to 6+ cores means you could have HT off and still run those same threads and apps but on individual physical cores.  That's why P3D is so flexible, it has to be able to cater for every type of hardware setup and use case.  The LM documentation covers AMs, so clearly they consider it's use to be justified in some scenarios.

 

 

[Cruachan 705]

4 hours ago, Ray Proudfoot said:

What’s the official advice from LM? Surely they know what works best for their code?

Hi Ray,

My guess is that they are assuming most users will be running with HT enabled since that is generally accepted as being the default position for the majority of HT capable Intel CPUs out there these days. Consequently, it seems reasonable to conclude that they would at least endeavour to exploit this capability in software.

Sadly, they cannot allow for all the performance vagaries which are a direct consequence of the seemingly boundless variety of hardware and end-user software setups. So, it’s perhaps fortunate that we at least have been afforded the opportunity to fine tune our CPUs for Prepar3D via the application of an Affinity Mask.

Also, don’t forget that most users like me have rigs that are not dedicated solely to running Prepar3D. In such situations we would be losing out by disabling HT in the BIOS. When I remind myself how ridiculously expensive that i7-5960X was you can bet your life that I want all it can give me in terms of performance, longevity and reliability. Fortunately that chip has proved to be a sound investment and continues to deliver all that I require as it continues rock stable while running a very broad spectrum of applications. Same goes for my factory overclocked 1080Ti and my Rampage V Extreme MoBo.

Regards,

Mike

Edited July 27, 2021 by Cruachan