On 01/08/2017 05:26, Longpeng (Mike) wrote: > > > On 2017/7/31 21:20, Paolo Bonzini wrote: > >> On 31/07/2017 14:27, David Hildenbrand wrote: >>>> I'm not sure whether the operation of get the vcpu's priority-level is >>>> expensive on all architectures, so I record it in kvm_sched_out() for >>>> minimal the extra cycles cost in kvm_vcpu_on_spin(). >>>> >>> as you only care for x86 right now either way, you can directly optimize >>> here for the good (here: x86) case (keeping changes and therefore >>> possible bugs minimal). >> >> I agree with Cornelia that this is inconsistent, so you shouldn't update >> me->in_kernmode in kvm_vcpu_on_spin. However, get_cpl requires >> vcpu_load on Intel x86, so Mike's patch is necessary (vmx_get_cpl -> >> vmx_read_guest_seg_ar -> vmcs_read32). >> > > Hi Paolo, > > It seems that other architectures(e.g. arm/s390) needn't to cache the result, > but x86 need, so I need to move 'in_kernmode' into kvm_vcpu_arch and only add > this field to x86, right? That's another way to do it, and I like it. >> This will cache the result until the next sched_in, so that > > 'until the next sched_in' --> Do we need to clear the result in sched in ? No, thanks. Paolo
