On Thu, 17 Aug 2017 11:16:59 +0200 Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > On 17/08/2017 09:36, Cornelia Huck wrote: > >> What if we just sent a "vcpu move" request to all vcpus with the new > >> pointer after it moved? That way the vcpu thread itself would be > >> responsible for the migration to the new memory region. Only if all > >> vcpus successfully moved, keep rolling (and allow foreign get_vcpu again). > >> > >> That way we should be basically lock-less and scale well. For additional > >> icing, feel free to increase the vcpu array x2 every time it grows to > >> not run into the slow path too often. > > > > I'd prefer the rcu approach: This is a mechanism already understood > > well, no need to come up with a new one that will likely have its own > > share of problems. > > What Alex is proposing _is_ RCU, except with a homegrown > synchronize_rcu. Using kvm->srcu seems to be the best of both worlds. I'm worried a bit about the 'homegrown' part, though. I also may be misunderstanding what Alex means with "vcpu move"...
