On Mon, Oct 22, 2018 at 01:27:27PM -0400, Waiman Long wrote: > >> I agree with Juergen on that. I would suggest rename the > >> vcpu_is_preempted hook into a more generic vcpu_stop_spinning, perhaps, > >> so different hypervisors can act on the information accordingly. Adding > >> an extra parameter is fine. > > No; no extra parameters. vcpu_is_preempted() is a simple and intuitive > > interface. Why would we want to make it complicated? > > Hyperv seems to do it in a somewhat different way by looking at the spin > counter and decide if it should continue. I don't know why they do that > and what advantage it has. > > The current patch is definitely not OK. A revised patch that makes use > of an existing paravirt hook will be more acceptable. Again, I would > like to see some performance figure and why they do it this way to see > if it is worthwhile to change the existing interface.
Note that there are vcpu_is_preempted() users that are not in a spin-loop.