Re: + paravirt-vmi-timer-patches.patch added to -mm tree

[Zachary Amsden]

Daniel Walker wrote:
> On Sat, 2007-01-06 at 12:37 -0800, Zachary Amsden wrote:
>
>   
> > > There is already a dynamic tick (NO_HZ) system in the -mm tree .. Given
> > > that this implementation seems unnecessary. Why do you need another
> > > different system to do this?
> > >   
> > >       
> > We don't.  This was written before the dynamic tick code, and now they 
> > need to be merged.  Until then, they can safely coexist.
> >     
>
> So really this can't go upstream till that merge happens. What's
> preventing you from just directly using NO_HZ without changes?
>   

For one thing, the fact that it doesn't account for stolen time.  But 
mostly because going through the regular PIT / APIC timer paths has a 
lot of overhead.  So we need a separate timer device, and weaving this 
in with the local APIC timer dependency for SMP on i386 requires changes 
on top of NO_HZ.

Zach
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