Re: [Xen-devel] Explore the source code

[Marco Tizzoni <marco.tizzoni@xxxxxxxxx>]

On Tue, Mar 31, 2009 at 12:40 PM, George Dunlap <dunlapg@xxxxxxxxx> wrote:

Hey Marco,

Sorry for not following up.  I think the scheduler is pretty well
contained in the following files:
xen/common/schedule.c
xen/common/sched_credit.c
xen/include/xen/sched.h

One thing to note about Xen that's different than Linux is that while
in Linux there's a per-process kernel stack, in Xen there's no per-VM
hypervisor stack. When schedule() is called, it completely throws away
all hypervisor stack and context, and returns directly to the target
VM.  For this reason, schedule() is never called directly, but a
schedule softirq is raised and called on the way back out of the
hypervisor anyway.

Thanks for your answer, with your help and David's book how to implement a new scheduler it's pretty clear now.
Also I'd have a look to device scheduling in order change its behaviour according to my new scheduler policies. Any suggestion on where to start?

Marco

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