[Xen-ia64-devel] RE: [Xen-devel] RE: [Patch] Fix IDLE issue with sedf scheduler on IA64

["Magenheimer, Dan (HP Labs Fort Collins)" <dan.magenheimer@xxxxxx>]

> >I think domain0 only goes in the waitq at one point -- when
> >it calls pal_halt_light to idle its virtual machine.  This
> >case could be easily changed (there is already some code there)
> >to ensure domain0 is always runnable.
> 
> As I said in another mail, too many pal_halt_light in Dom0's 
> idle loop is even worse than current IDLE domain. (At lease 
> unmodified dom0 can't change that behavior)

You misunderstand what I was suggesting:  When the hypervisor
recognizes that a domain did a pal_halt_light:

if (current == dom0) {
        if (current is_the_only_non_idle_domain_on_the_run_queue) {
                REAL_pal_halt_light;  // processor to low power state
                return; // back to domain0
      }
      else do_sched_op(SCHEDOP_yield);
}
else do_sched_op(SCHEDOP_yield);

Dan


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