Re: [PATCH v4 5/5] KVM: LAPIC: Narrow the timer latency between wait_lapic_expire and world switch

[Sean Christopherson]

On Tue, May 18, 2021, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> 
> Let's treat lapic_timer_advance_ns automatic tuning logic as hypervisor
> overhead, move it before wait_lapic_expire instead of between wait_lapic_expire 
> and the world switch, the wait duration should be calculated by the 
> up-to-date guest_tsc after the overhead of automatic tuning logic. This 
> patch reduces ~30+ cycles for kvm-unit-tests/tscdeadline-latency when testing 
> busy waits.
> 
> Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> ---

Reviewed-by: Sean Christopherson <seanjc@xxxxxxxxxx>