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Framerate issues, possibly related to AMD Ryzen 7 CPU

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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Lydiot » Tue Oct 06, 2020 8:48 pm

will check, thanks
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Wed Oct 07, 2020 6:19 am

Hooray wrote in Tue Oct 06, 2020 7:25 pm:see the OSG docs, it's just an environment variable, i.e. something like OSG_NUM_DATABASE_THREADS


I found viewtopic.php?f=2&t=2812. Will try, I'm very curious.
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Hooray » Wed Oct 07, 2020 6:28 am

Note that according to findings shared by Richard, when testing the database pager extensively (running with 20 DB pager threads), the main problem is the way that random objects (buildings, vegetation) are inserted into the scene graph doesn't seem to be compatible with lots of pager threads: https://sourceforge.net/p/flightgear/ma ... /36536293/
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Wed Oct 07, 2020 2:57 pm

I tested OSG_NUM_DATABASE_THREADS, I was able use 7 threads, I had only 2 CTD on possible memory corruption. Scenery loading time is blazing fast, RAM consumption too, when I started over Central Park, FG in few seconds ate almost 15 GB RAM :twisted:

Image

FPS is still low, with A320family only 5 fps

Image

Not enough for reconstruction of the Hudson Miracle...
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Hooray » Wed Oct 07, 2020 3:19 pm

Thanks for reporting back here, since this option seems new to some users, have you considered contributing your findings/instructions to the wiki ?
You could start by taking screen shots to illustrate how configure & start up FlightGear accordingly, and then add screen shots to visualize the utilization of your cores.

I have created a stub here: http://wiki.flightgear.org/Howto:Using_ ... er_Threads

Thinking about it, another idea would be to expose the number of DB threads as a startup option/property, so that this can be easily configured by users - possibly even as part of the hackathon ? :D

PS: You might want to try disabling those features that are known to interfere with aggressive threading.
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Wed Oct 07, 2020 5:02 pm

Usage OSG_NUM_DATABASE_THREADS other than 1 needs massive testing, it is too early to make standard from OSG_NUM_DATABASE_THREADS >1. I had 2 crashes to desktop with message Possible memory corruption.
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Hooray » Wed Oct 07, 2020 5:12 pm

It's more likely a race condition - but the point wasn't to make this the default, rather expose it so that we have wider exposure/more testing, and hopefully better bug reports.
As has been said, you might be able to work around some of these issues by disabling related features (mostly the shader-based autogen stuff).
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby vnts » Thu Oct 08, 2020 5:29 am

V12 wrote in Wed Oct 07, 2020 2:57 pm:
FPS is still low, with A320family only 5 fps


The craft's current optimisation is interfering right now. Does your FPS improve with the ufo?

If it doesn't change at all thing that is bottlenecking performance on your system hasn't changed, and you should find what that is first. It it improves a bit, maybe part of the workload of that thread got moved to another.

You shouldn't have had that low FPS in the first place, or to put it another way, if other people do the same optimisation their FPS when CPU bound would also improve by the same amount, and your FPS will still be oddly slow compared to them.

V12 wrote in Tue Oct 06, 2020 8:48 am:On W10 64bit FG performance is even lower than on Linux...
One important remark :
When FG loading scenery, CPU utilization is always around 25%. When the scenery has been loaded, CPU utilization fall to 12-13%. Then there is another problem - in my tests I never have 100% utilization on 1 core, or more than 50% on 2 cores :

Image

Check htop window left on the screenshot.

htop doesn't give utilisation for each thread? That looks like utilisation per core. The OS might move threads around from core to core to keep temperatures cool or whatever, so utilisation of any one core doesn't reach 100%.

Try Process Explorer (link) on your windows install in the situation where you get 12.5% overall CPU utilisation. Try it without the OSG_NUM_DATABASE_THREADS tweak to deal with one problem at a time.

On mine:
DrawThreadPerContext:
Image
CullThreadPerCameraDrawThreadPerContext:
Image

If you post your version with 12.5 FPS devs should be able to get a hint at what thread isn't doing anything compared to when you get 25%, or compared to other people. Process explorer also shows the call stack for threads which should give an indication of what thread is having a problem.

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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Thu Oct 08, 2020 9:34 am

As I wrote in previous post, when OSG_NUM_DATABASE_THREADS=7, scenery loading is lightning fast, CPU usage is almost 100%. After scenery load, CPU utilization fall to 13%. With UFO I have 9 fps, with A320family only 5. With Concorde 7, 737-800YV 8 fps.
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby vnts » Thu Oct 08, 2020 9:44 am

V12 wrote in Thu Oct 08, 2020 9:34 am: when OSG_NUM_DATABASE_THREADS=7, scenery loading is lightning fast, CPU usage is almost 100%. After scenery load, CPU utilization fall to 13%. With UFO I have 9 fps..

"After scenery load, CPU utilization fall to 13%". So essentially your FPS problem with your system is not fixed. You should find out why. Fast scenery loading is an unrelated bonus.

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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby wkitty42 » Thu Oct 08, 2020 11:44 am

vnts wrote in Thu Oct 08, 2020 9:44 am:"After scenery load, CPU utilization fall to 13%". So essentially your FPS problem with your system is not fixed. You should find out why. Fast scenery loading is an unrelated bonus.

i'd love to upvote this response so many times ;)
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Richard » Fri Oct 09, 2020 5:52 pm

@V12 your problem is that you are CPU bound in the OSG rendering - 108ms is ridiculously high and indicates poor single core performance. GPU is doing OK

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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby Johan G » Sat Oct 10, 2020 7:42 am

Richard wrote in Fri Oct 09, 2020 5:52 pm:[...] 108ms is ridiculously high and indicates poor single core performance.

V12 wrote in Wed Sep 23, 2020 7:00 am:AMD Ryzen 7 CPUs have poor single core performance in comparison with Intel Core. This fact is not visible in benchmark, only in real apps.
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Sat Oct 10, 2020 6:45 pm

Yes, I know that fact. In singlecore benchmarks is 3700X comparable with i5, bit slower than i7 in singlecore. But in older non optimized apps is Ryzen like a speedbrake, Things going better in multithreaded workstation apps, 3700X is significantly faster than i7-9700K. I made mistake year ago :evil:
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Re: Framerate issues, possibly related to AMD Ryzen 7 CPU

Postby V12 » Tue Oct 13, 2020 7:49 pm

Strange observation - today I tested NY scenery on old ElitBook with i7-3160Q and Quadro K1000M. CPU load 70% (3 threads for scenery assembly), GPU at 70% and 8 fps over Central park. In all other single threaded apps is this historic machine 2 times slower than R7-3700X.
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