[Xen-devel] Question regarding Xen scheduler

["Zytaruk, Kelly" <Kelly.Zytaruk@xxxxxxx>]

I would like to ask a question as to how the Xen scheduler handles certain 
situations.  
From everything that I have read I understand that the scheduler treats Dom0 
just like any other DomU in regards to scheduling.

My question is in regards to interrupt handlers, critical sections and kernel 
code.  Is the Xen scheduler aware of whether the Dom0 is executing in kernel 
code versus user mode code?  Can Dom0 kernel mode code be interrupted by the 
Xen scheduler and then a DomU run for a while before returning back to Dom0 
kernel mode code?

What about interrupt handling routines either in Dom0 or DomU.  Can a Task 
switch to another DomU / Dom0 occur if in the middle of an interrupt handler?

What if I am doing something time critical or sequence critical that can't be 
interrupted?  Is there a way to tell the Xen scheduler that "I am in a critical 
section and can't be interrupted by another Dom" so that Xen won't task switch 
until I am done?

Other than reading the source code is there a good reference that I can read 
for Xen internal details and architecture?  

Thanks,
Kelly



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