V12 wrote in Thu Sep 24, 2020 9:05 am:BTW, on my system I can't disable SMT
You should be able to disable via bios?
Google says Ryzen CPUs, at least when they came out, benefited from turning SMT off for a slight increase in some 3d programse.g. for your R7 3700X [1]. Since you use a major linux distribution like Ubuntu, the scheduler should be pretty good and up-to date by now.
V12 wrote in Thu Sep 24, 2020 9:05 am:I had this problem on i5-2550K on Win 7, on Ubuntu from 14 to latest 20, this problem exists now on R7 3700X on Win 10 and Ubuntu 20.04.
On your previous systems you might have been GPU bound, or maybe didn't know FG/settings as well as you do now if you started somewhat recently..
Focusing on you current system, since you run P3D you have a Windows install too? Try that.
Reproducible test: for max CPU utilisation by threads:
- UFO, Manhattan coordinates 40.783333, -73.966667 (can just copy/paste into location bar on launcher). Measured while scenery is still loading.
- Make sure vsync is off, FPS throttle is off, not GPU bound (utilisation <100%)
- Default lods (Can try with expanded LoD as well, to see why CPU utilisation changed)
- On Windows: Try process explorer (link) > right click fgfs.exe > click properties > click threads.
- On Linux google says you can try ps [2]
My results for UFO on a 4 core i5 (a thread maxing out a core takes up 1/4=25%):
DrawThreadPerContext: link
CullThreadPerCameraDrawThreadPerContext: link
There are often two high CPU usage threads, and while scenery is loading CPU usage doesn't go below 50%. I took these screens when utilisation was somewhat high. FG has 20 threads, with an extra thread for the second option as expected. The 2nd highest usage thread usually has lower load for the second option probably showing the split into an extra thread. There are 3-4 threads with a noticeable load.
CPU usage for CullThreadPerCameraDrawThreadPerContext was around 70% of 4 cores in the screens, or 2.8 cores. So with 16 cores you should get at least 2.8+/16=17.5%+. With SMT off (8 cores) it should be at least 35%+.
Kind regards