Messages in this thread | | | From | Vitaly Kuznetsov <> | Subject | Re: [PATCH v4 RESEND 3/5] KVM: x86: hyperv: use get_vcpu_by_vpidx() in kvm_hv_flush_tlb() | Date | Mon, 17 Sep 2018 10:32:55 +0200 |
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Paolo Bonzini <pbonzini@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
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