From: Sean Christopherson <sean.j.christopherson@intel.com>
To: Wanpeng Li <kernellwp@gmail.com>
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
"Paolo Bonzini" <pbonzini@redhat.com>,
"Radim Krčmář" <rkrcmar@redhat.com>,
"Liran Alon" <liran.alon@oracle.com>
Subject: Re: [PATCH 1/3] KVM: LAPIC: Extract adaptive tune timer advancement logic
Date: Mon, 13 May 2019 12:39:40 -0700 [thread overview]
Message-ID: <20190513193940.GL28561@linux.intel.com> (raw)
In-Reply-To: <1557401361-3828-2-git-send-email-wanpengli@tencent.com>
On Thu, May 09, 2019 at 07:29:19PM +0800, Wanpeng Li wrote:
> From: Wanpeng Li <wanpengli@tencent.com>
>
> Extract adaptive tune timer advancement logic to a single function.
Why?
>
> Cc: Paolo Bonzini <pbonzini@redhat.com>
> Cc: Radim Krčmář <rkrcmar@redhat.com>
> Cc: Sean Christopherson <sean.j.christopherson@intel.com>
> Cc: Liran Alon <liran.alon@oracle.com>
> Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
> ---
> 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
>
next prev parent reply other threads:[~2019-05-13 19:39 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-09 11:29 [PATCH 0/3] KVM: LAPIC: Optimize timer latency further Wanpeng Li
2019-05-09 11:29 ` [PATCH 1/3] KVM: LAPIC: Extract adaptive tune timer advancement logic Wanpeng Li
2019-05-13 19:39 ` Sean Christopherson [this message]
2019-05-14 0:59 ` Wanpeng Li
2019-05-09 11:29 ` [PATCH 2/3] KVM: LAPIC: Fix lapic_timer_advance_ns parameter overflow Wanpeng Li
2019-05-13 19:14 ` Sean Christopherson
2019-05-09 11:29 ` [PATCH 3/3] KVM: LAPIC: Optimize timer latency further Wanpeng Li
2019-05-13 19:54 ` Sean Christopherson
2019-05-14 1:45 ` Wanpeng Li
2019-05-14 10:56 ` Wanpeng Li
2019-05-14 16:45 ` Sean Christopherson
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