Re: [PATCH 1/3] KVM: LAPIC: Extract adaptive tune timer advancement logic
From: Wanpeng Li
Date: Mon May 13 2019 - 20:59:38 EST
On Tue, 14 May 2019 at 03:39, Sean Christopherson
<sean.j.christopherson@xxxxxxxxx> wrote:
>
> On Thu, May 09, 2019 at 07:29:19PM +0800, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> >
> > Extract adaptive tune timer advancement logic to a single function.
>
> Why?
Just because the function wait_lapic_expire() is too complex now.
Regards,
Wanpeng Li
>
> >
> > Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
> > Cc: Radim KrÄmÃÅ <rkrcmar@xxxxxxxxxx>
> > Cc: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
> > Cc: Liran Alon <liran.alon@xxxxxxxxxx>
> > Signed-off-by: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> > ---
> > arch/x86/kvm/lapic.c | 57 ++++++++++++++++++++++++++++++----------------------
> > 1 file changed, 33 insertions(+), 24 deletions(-)
> >
> > diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> > index bd13fdd..e7a0660 100644
> > --- a/arch/x86/kvm/lapic.c
> > +++ b/arch/x86/kvm/lapic.c
> > @@ -1501,11 +1501,41 @@ static inline void __wait_lapic_expire(struct kvm_vcpu *vcpu, u64 guest_cycles)
> > }
> > }
> >
> > -void wait_lapic_expire(struct kvm_vcpu *vcpu)
> > +static inline void adaptive_tune_timer_advancement(struct kvm_vcpu *vcpu,
> > + u64 guest_tsc, u64 tsc_deadline)
> > {
> > struct kvm_lapic *apic = vcpu->arch.apic;
> > u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns;
> > - u64 guest_tsc, tsc_deadline, ns;
> > + u64 ns;
> > +
> > + if (!apic->lapic_timer.timer_advance_adjust_done) {
> > + /* too early */
> > + if (guest_tsc < tsc_deadline) {
> > + ns = (tsc_deadline - guest_tsc) * 1000000ULL;
> > + do_div(ns, vcpu->arch.virtual_tsc_khz);
> > + timer_advance_ns -= min((u32)ns,
> > + timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
> > + } else {
> > + /* too late */
> > + ns = (guest_tsc - tsc_deadline) * 1000000ULL;
> > + do_div(ns, vcpu->arch.virtual_tsc_khz);
> > + timer_advance_ns += min((u32)ns,
> > + timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
> > + }
> > + if (abs(guest_tsc - tsc_deadline) < LAPIC_TIMER_ADVANCE_ADJUST_DONE)
> > + apic->lapic_timer.timer_advance_adjust_done = true;
> > + if (unlikely(timer_advance_ns > 5000)) {
> > + timer_advance_ns = 0;
> > + apic->lapic_timer.timer_advance_adjust_done = true;
> > + }
> > + apic->lapic_timer.timer_advance_ns = timer_advance_ns;
> > + }
>
> This whole block is indented too far.
>
> > +}
> > +
> > +void wait_lapic_expire(struct kvm_vcpu *vcpu)
> > +{
> > + struct kvm_lapic *apic = vcpu->arch.apic;
> > + u64 guest_tsc, tsc_deadline;
> >
> > if (apic->lapic_timer.expired_tscdeadline == 0)
> > return;
> > @@ -1521,28 +1551,7 @@ void wait_lapic_expire(struct kvm_vcpu *vcpu)
> > if (guest_tsc < tsc_deadline)
> > __wait_lapic_expire(vcpu, tsc_deadline - guest_tsc);
> >
> > - if (!apic->lapic_timer.timer_advance_adjust_done) {
> > - /* too early */
> > - if (guest_tsc < tsc_deadline) {
> > - ns = (tsc_deadline - guest_tsc) * 1000000ULL;
> > - do_div(ns, vcpu->arch.virtual_tsc_khz);
> > - timer_advance_ns -= min((u32)ns,
> > - timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
> > - } else {
> > - /* too late */
> > - ns = (guest_tsc - tsc_deadline) * 1000000ULL;
> > - do_div(ns, vcpu->arch.virtual_tsc_khz);
> > - timer_advance_ns += min((u32)ns,
> > - timer_advance_ns / LAPIC_TIMER_ADVANCE_ADJUST_STEP);
> > - }
> > - if (abs(guest_tsc - tsc_deadline) < LAPIC_TIMER_ADVANCE_ADJUST_DONE)
> > - apic->lapic_timer.timer_advance_adjust_done = true;
> > - if (unlikely(timer_advance_ns > 5000)) {
> > - timer_advance_ns = 0;
> > - apic->lapic_timer.timer_advance_adjust_done = true;
> > - }
> > - apic->lapic_timer.timer_advance_ns = timer_advance_ns;
> > - }
> > + adaptive_tune_timer_advancement(vcpu, guest_tsc, tsc_deadline);
> > }
> >
> > static void start_sw_tscdeadline(struct kvm_lapic *apic)
> > --
> > 2.7.4
> >