From: Wanpeng Li <wanpen...@tencent.com> 5000 guest cycles delta is easy to encounter on desktop, per-vCPU lapic_timer_advance_ns always keeps at 1000ns initial value, lets loose fluctuation filter a bit to make auto tune can make some progress.
Signed-off-by: Wanpeng Li <wanpen...@tencent.com> --- v1 -> v2: * separate defines for ns vs cycles arch/x86/kvm/lapic.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 3a3a685..7bfc3c0 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -66,9 +66,10 @@ #define X2APIC_BROADCAST 0xFFFFFFFFul static bool lapic_timer_advance_dynamic __read_mostly; -#define LAPIC_TIMER_ADVANCE_ADJUST_MIN 100 -#define LAPIC_TIMER_ADVANCE_ADJUST_MAX 5000 -#define LAPIC_TIMER_ADVANCE_ADJUST_INIT 1000 +#define LAPIC_TIMER_ADVANCE_EXPIRE_MIN 100 +#define LAPIC_TIMER_ADVANCE_EXPIRE_MAX 10000 +#define LAPIC_TIMER_ADVANCE_NS_INIT 1000 +#define LAPIC_TIMER_ADVANCE_NS_MAX 5000 /* step-by-step approximation to mitigate fluctuation */ #define LAPIC_TIMER_ADVANCE_ADJUST_STEP 8 @@ -1488,8 +1489,8 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu, u64 ns; /* Do not adjust for tiny fluctuations or large random spikes. */ - if (abs(advance_expire_delta) > LAPIC_TIMER_ADVANCE_ADJUST_MAX || - abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_ADJUST_MIN) + if (abs(advance_expire_delta) > LAPIC_TIMER_ADVANCE_EXPIRE_MAX || + abs(advance_expire_delta) < LAPIC_TIMER_ADVANCE_EXPIRE_MIN) return; /* too early */ @@ -1504,8 +1505,8 @@ static inline void adjust_lapic_timer_advance(struct kvm_vcpu *vcpu, timer_advance_ns += ns/LAPIC_TIMER_ADVANCE_ADJUST_STEP; } - if (unlikely(timer_advance_ns > LAPIC_TIMER_ADVANCE_ADJUST_MAX)) - timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; + if (unlikely(timer_advance_ns > LAPIC_TIMER_ADVANCE_NS_MAX)) + timer_advance_ns = LAPIC_TIMER_ADVANCE_NS_INIT; apic->lapic_timer.timer_advance_ns = timer_advance_ns; } @@ -2302,7 +2303,7 @@ int kvm_create_lapic(struct kvm_vcpu *vcpu, int timer_advance_ns) HRTIMER_MODE_ABS_HARD); apic->lapic_timer.timer.function = apic_timer_fn; if (timer_advance_ns == -1) { - apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_ADJUST_INIT; + apic->lapic_timer.timer_advance_ns = LAPIC_TIMER_ADVANCE_NS_INIT; lapic_timer_advance_dynamic = true; } else { apic->lapic_timer.timer_advance_ns = timer_advance_ns; -- 2.7.4