Re: Linux spin lock enhancement on xen

[Mukesh Rathor <mukesh.rathor@oracle.com>]

On Wed, 18 Aug 2010 18:09:22 +0100
Keir Fraser <keir.fraser@eu.citrix.com> wrote:

> On 18/08/2010 17:37, "Jeremy Fitzhardinge" <jeremy@goop.org> wrote:
> 
> > I don't see why the guest should micromanage Xen's scheduler
> > decisions. If a VCPU is waiting for another VCPU and can put itself
> > to sleep in the meantime, then its up to Xen to take advantage of
> > that newly freed PCPU to schedule something.  It may decide to run
> > something in your domain that's runnable, or it may decide to run
> > something else.  There's no reason why the spinlock holder is the
> > best VCPU to run overall, or even the best VCPU in your domain.
> > 
> > My view is you should just put any VCPU which has nothing to do to
> > sleep, and let Xen sort out the scheduling of the remainder.
> 
> Yeah, I'm no fan of yield or yield-to type operations. I'd reserve
> the right to implement both of them as no-op.
> 
>  -- Keir
> 

I think making them advisory makes sense. Ultimately xen decides. 

thanks,
Mukesh