Limited by MainThread?

[Andreas Stangenes 1,628]

Using the FPS tools from the devkit I get a remark saying "limited by mainthread". What does that mean?

[Jetman67 517]

Good question, following

[ChaoticBeauty 6,692]

It means that you are limited by your CPU, more specifically by one of your CPU's cores/threads.

[virtuali 4,421]

It means whatever is limiting fps, comes from one of the many things done by the CPU ( like AI traffic, road traffic,  flight model, streaming data, etc. ), not pure rendering.

Note that, if you lower the relevant settings so that you could not be limited by the CPU, it's possible the counter would then say "limited by the GPU", because that message indicates the 1st most limiting thing at any time.

The dev mode fps counter has an "ideal" target, that is 60 fps, or 16.67 ms of rendering time. If you keep an eye on the rendering times for each item ( MainThread, CoherentGT, GPU, etc. ), each one will be shown in GREEN, as long it stays under 16.67 ms. If all items are below that, the big fps counter itself will turn green, meaning you are in the ideal situation.

Coherent GT time, is the impact of 2D graphic, like glass cockpit instruments, the Vfr map, and even the overlays on screen when you go in outside view. You'll notice it goes to almost 0 if you are in "Drone Camera" mode, where no 2D elements are present on screen, no instruments or overlays.

[Andreas Stangenes 1,628]

I have an i7-6700k @4.4ghz with ht on. I hear so many people rave on how this cpu is pretty decent with ht on, but im having the darndest time trying to get my sim to run smoothly. 

Edited August 26, 2020 by Andreas Stangenes

[MrFuzzy 2,118]

CPU bottleneck: the main thread is the most taxed logical core of your system. You may have 16 cores / 32 threads but if one of them is pegged to 100% occupation, the game will slow down to the speed of that thread.

Example where thread no.3 is saturated and acts as a bottleneck:

[roi1862 602]

In general my CPU is almost always on 50%-60% usage while the GPU is 95% to 99%.

[MrFuzzy 2,118]

4 minutes ago, Andreas Stangenes said:

I have an i7-6700k @4.4ghz with ht on. I hear so many people rave on how this cpu is pretty decent with ht on, but im having the darndest time trying to get my sim to run smoothly. 

My CPU is similar (7700K at 4.7 with AVX) and the sim is smooth, around 60-70 fps (40-50 over big cities) at Ultra/High-end details. The CPU usage is always between 40 and 60%.

However I have periodical stutters mainly due to Coherent GT Draw, hopefully they will fix it because it is the main reason why liners are much heavier for the CPU than GA aircraft without screens.

[Hippo 34]

15 minutes ago, roi1862 said:

In general my CPU is almost always on 50%-60% usage while the GPU is 95% to 99%.

But I assume that that's the average across all cores?  I'm similar, with my CPU at 50%, GPU at 99%-100%, but one of my CPU logical cores (12), runs much higher than all others, hitting around 80-90%.  The others are 20-50%.  If I were to replace my 1080 Ti with a 2080 Ti, I might find my GPU dropping, and being limited instead by one of my CPU cores at 100%  (though average CPU much lower), like the screenshot above.

Sorry if you're already aware of all this, but many people do post average CPU, when they really should also be looking at what the individual cores are doing.

 

Edited August 26, 2020 by Hippo

[roi1862 602]

3 minutes ago, Hippo said:

But I assume that that's the average across all cores?  I'm similar, with my CPU at 50%, GPU at 99%-100%, but one of my CPU logical cores (12), runs much higher than all others, hitting around 80-90%.  The others are 20-50%.  If I were to replace my 1080 Ti with a 2080 Ti, I might find my GPU dropping, and being limited instead by one of my CPU cores at 100%  (though average CPU much lower), like the screenshot above.

Sorry if you're already aware of all this, but many people do post average CPU, when they really should also be looking at what the individual cores are doing.

 

Funny the core that works hardest on my end is the last logical core. 5820K 

[Colonel X 1,430]

20 minutes ago, MrFuzzy said:

My CPU is similar (7700K at 4.7 with AVX) and the sim is smooth, around 60-70 fps (40-50 over big cities) at Ultra/High-end details. The CPU usage is always between 40 and 60%.

However I have periodical stutters mainly due to Coherent GT Draw, hopefully they will fix it because it is the main reason why liners are much heavier for the CPU than GA aircraft without screens.

The periodical stutters completely vanish when using the Process Lasso trick.

[Andreas Stangenes 1,628]

1 hour ago, Colonel X said:

The periodical stutters completely vanish when using the Process Lasso trick.

Sorry I missed the lasso trick. Can you link it please?

[MrFuzzy 2,118]

1 hour ago, Colonel X said:

The periodical stutters completely vanish when using the Process Lasso trick.

Do you mean disabling Windows dynamic thread priority? I tried it before without results, I will try it again this evening.

Thanks.

[MrFuzzy 2,118]

7 minutes ago, Andreas Stangenes said:

Sorry I missed the lasso trick. Can you link it please?

 

[Andreas Stangenes 1,628]

I downloaded process lasso, but the windows dynamic process thing was already disabled. However, what I noticed was that the process was listed as below normal priority. I put it to normal.