Paolo Bonzini <pbonz...@redhat.com> writes: > On 22/08/2018 12:18, Vitaly Kuznetsov wrote: >> VP_INDEX almost always matches VCPU id and get_vcpu_by_vpidx() is fast, >> use it instead of traversing full vCPU list every time. > > ... but if it doesn't, the algorithm is now quadratic, isn't i?
Yes, I even had an implementation with a logarythmic search back in v2 but we had a discussion with Roman and he convinced me this is an overkill and not currently required. It seems that with Qemu this is true indeed, vp_index always matches vcpu is but in case some other userspace decides to break this unwritten rule users may experience significant slowdown. -- Vitaly
