I have a particular project template, where I have serious problems with audio drop outs due to high CPU load. While the project only uses about 20% of total CPU power, the first thread (out of 12) in the Performance module is often going into the red area and then sometimes stops the audio engine. With load balancing activated, the first thread goes down close to zero, but the drop outs happen nonetheless. For whatever reason, the problem is only with that particular project, while other projects don't cause drop outs, even when they have much higher total CPU load.

I can fix the problem by changing the power plan settings. By setting the minimum CPU limit to 100% instead of 5%, the first thread drops to about 60% (without load balancing) and the drop outs no longer happen (with or without balancing).

However, I wonder about three things:
1. Why are there drop outs for that particular project, but not for others with even higher CPU load?
2. Why doesn't load balancing help to avoid the drop outs? According to Performance module, no single thread is overly loaded, but nonetheless the audio engine stops. Could this be a bug that Sonar detects possible overload without considering if load balancing is active?
3. Why is Sonar not able to ensure that the CPU provides enough power, if it is there in principle, but reduced by power management?

You might consider altering the value of a Sonar parameter in Edit>Preferences>Audio>Configuration File, called ThreadSchedulingModel, to a value of 2, which helps with the distribution of things across multiple CPU cores.
 
Additionally, if you load up large numbers of instruments in multi-timbral synths like Kontakt, into a single instance, Sonar won't be able to split that work up.  Noel has commented on this in the past, and has suggested that CPU work is better distributed by instead keeping any one Kontakt instance loaded with a smaller number of instruments and using multiple Kontakt instances to house the needed instruments.  (I generally keep any single instance of Kontakt down to no more than 5-6 instruments, and just use multiple instances).
 
Hope any of the above helps you, 
 
Bob Bone
 

Thanks for your help.

Using ThreadSchedulingModel 2 gives a better distribution between threads in Performance module when balancing is off (looks similar to balancing on then), but doesn't prevent the drop outs.

I tried to disable each single instrument plugin (and several effects), none of it made a change. There is one Kontakt instance with 2 instruments, in other projects I have several Kontakt instances with up to 4 instruments.

The odd thing is that I have drop outs due to CPU load, but all threads in Permformance module are below 50%.

Dropouts usually have a TOAST message popup with a link to the help for resolution. The help suggests a few settings to adjust http://www.cakewalk.com/Documentation?product=SONAR&language=3&help=Troubleshooting.23.html
 

I tried all those suggestions. But the problem is definitely CPU load, and this is not addressed. My main concern is that I get drop outs from CPU load, but neither CPU total nor single threads seem to be overloaded. Hence, I wonder if there is something wrong with load balancing.

I don't think Windows Power Management is capable of responding properly to the rapid real-time changes in load that a DAW can generate. It's generally recommended to disable all CPU-throttling in a DAW. This means disabling Speedstep, C-States and Turboboost in BIOS, and setting Windows Power Management to High Performance.
 
You should also run LatencyMon, and make sure you aren't getting spikes in Deferred Procedure Call latency.
 
     http://www.resplendence.com/latencymon
 
 
 

Admittedly, optimizing Windows for high performance is much recommended when running a DAW. I mainly wondered why I never had any problems like this before, and why load balancing didn't help, when without load balancing, the problem was obviously caused by the first thread going into red (approaching 100% load).

Ralph, Anything different about this project than any of your others ?
Settings, plug ins, exc ? I know you have probably already gone through all this already but I would look for differences between projects and if I could not find any, start a new project and drag the data in to it.
Re- create the whole project again and see if you still have the same issue. if you don't, then its possible something became corrupt in the project itself. Good luck buddy

I guess it's the combination of VST-plugins. If I disable enough plugins, the load is low enough to prevent drop outs. But no particular plugin seems to be the one that makes the difference.
 
I think I will have to live with changing the power settings when working with that particular project. (I don't want to have them permanently high.)

Check out this free utility called Full Throttle, which lets you override your system power plan for specific applications. The only catch is that you must run the application as Administrator in order to grant it permissions for changing power settings.