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Subject[PATCH v2] KVM: LAPIC: Retry tune per-vCPU timer_advance_ns if adaptive tuning goes insane
Date
From: Wanpeng Li <wanpengli@tencent.com>

Retry tune per-vCPU timer_advance_ns if adaptive tuning goes insane which
can happen sporadically in product environment.

Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Wanpeng Li <wanpengli@tencent.com>
---
v1 -> v2:
* retry max 10 times if adaptive tuning goes insane

arch/x86/kvm/lapic.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 95affa5..bd0dbe5 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1538,6 +1538,7 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu,
struct kvm_lapic *apic = vcpu->arch.apic;
u32 timer_advance_ns = apic->lapic_timer.timer_advance_ns;
u64 ns;
+ uint retry_count = 0;

/* too early */
if (advance_expire_delta < 0) {
@@ -1556,8 +1557,10 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu,
if (abs(advance_expire_delta) < 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;
+ timer_advance_ns = 1000;
+ apic->lapic_timer.timer_advance_adjust_done = false;
+ if (++retry_count > 10)
+ apic->lapic_timer.timer_advance_adjust_done = true;
}
apic->lapic_timer.timer_advance_ns = timer_advance_ns;
}
--
1.8.3.1
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