Re: [Xen-devel] [PATCH RFC V9 0/19] Paravirtualized ticket spinlocks

[Raghavendra K T <raghavendra.kt@xxxxxxxxxxxxxxxxxx>]

On 07/11/2013 03:41 PM, Gleb Natapov wrote:
> On Thu, Jul 11, 2013 at 03:40:38PM +0530, Raghavendra K T wrote:
> > > > > > Gleb,
> > > > > > Can you elaborate little more on what you have in mind regarding per
> > > > > > VM ple_window. (maintaining part of it as a per vm variable is clear
> > > > > > to
> > > > > >   me), but is it that we have to load that every time of guest entry?
> > > > > Only when it changes, shouldn't be to often no?
> > > > Ok. Thinking how to do. read the register and writeback if there need
> > > > to be a change during guest entry?
> > > Why not do it like in the patch you've linked? When value changes write it
> > > to VMCS of the current vcpu.
> > Yes. can be done. So the running vcpu's ple_window gets updated only
> > after next pl-exit. right?
> I am not sure what you mean. You cannot change vcpu's ple_window while
> vcpu is in a guest mode.
I agree with that. Both of us are on the same page.
 What I meant is,
suppose the per VM ple_window changes when a vcpu x of that VM  was running,
it will get its ple_window updated during next run.


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