Messages in this thread | | | Subject | Re: [PATCH v7] KVM: LAPIC: Apply change to TDCR right away to the timer | From | Paolo Bonzini <> | Date | Fri, 6 Oct 2017 16:21:23 +0200 |
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On 06/10/2017 16:01, Wanpeng Li wrote: > + if (!apic->lapic_timer.period) > + return; > + > + now = ktime_get(); > + remaining = ktime_sub(apic->lapic_timer.target_expiration, now); > + if (ktime_to_ns(remaining) < 0) > + remaining = 0; > + delta = mod_64(ktime_to_ns(remaining), apic->lapic_timer.period);
I think this shouldn't be happening. If it does, I'm not sure the mod is the right thing to do, so I'd just use ktime_to_ns(remaining).
So perhaps let's simplify all this to:
ns_remaining_old = ktime_to_ns(remaining); ns_remaining_new = mul_u64_u32_div(ns_remaining_old, apic->divide_count, old_divisor);
because below you're calling nsec_to_cycles but remaining is not expressed in nanoseconds.
> + if (!delta) > + return; > + > + delta = delta * apic->divide_count / old_divisor; > + > + limit_periodic_timer_frequency(apic);
This should be done before all the "if"s (which should not be there in v8, but you should still call it before "now = ktime_get();").
Paolo
> + apic->lapic_timer.tscdeadline += nsec_to_cycles(apic->vcpu, delta) - > + nsec_to_cycles(apic->vcpu, remaining); > + apic->lapic_timer.target_expiration = ktime_add_ns(now, delta); > +}
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