VBox influences applications running on other CPUs

[Christian Menard]

Hi,

Thanks for the patch! I tried various configurations, but the system keeps 
behaving strangely.

I dropped the priority setting, because with priorities I ran into the problem 
I described before - the VM hangs during bootup without any error messages or 
a clear reason. However, I removed a few printfs (mostly "attempted to 
read/write to non-existing port") to get a cleaner log and discovered that it 
helps to avoid the issue.

When I setup a system that starts the Android-VM and Nitpicker in parallel on 
top of my Framebuffer-Multiplexer but does not start any nitpicker apps, 
everything works fine in single- and multi-processor case. However, as soon as 
I start a nitpicker app like liquid_fb, the system gets very slow while the 
android kernel is booting. The kernel boot takes more than 30 minutes (usually 
a few seconds) and everything else is very slow as well. In the case where 
virtualbox runs on a separate CPU it gets even worse. Once the kernel boot 
completed, the system runs fast again. In this state starting virtualbox on 
another CPU helps, the system in general responds faster and has better 
performance.

I wonder why an app running in parallel to virtualbox influences the 
performance of the whole system so drastically. First I thought it might be 
related to my Framebuffer multiplexer, but the problem remains when starting 
virtualbox in a liquid_fb. Do you have any suggestions?

Thanks
Christian

On Monday 10 November 2014 11:26:44 Alexander Boettcher wrote:
> Hello Christian,
> 
> On 09.11.2014 14:51, Alexander Boettcher wrote:
> > The core services and init are running on the boot CPU. By moving all
> > critical servers to another CPU (as done in your run script) you get a
> > lot of cross CPU switching overhead, whenever the services call init or
> > core.
> > 
> > The better approach is to start VBox on another CPU instead, actually I
> > doesn't know whether this is already works ...
> 
> please try following attached patch. With it VBox can be started also on
> another CPU then the boot CPU.
> 
> Does it work for you ?
> 
> Alex.