Re: [PATCH 2/2] KVM: LAPIC: micro-optimize fixed mode ipi delivery

[Wanpeng Li]

On Tue, 12 Nov 2019 at 05:59, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote:
>
> On 09/11/19 08:05, Wanpeng Li wrote:
> > From: Wanpeng Li <wanpengli@xxxxxxxxxxx>
> >
> > After disabling mwait/halt/pause vmexits, RESCHEDULE_VECTOR and
> > CALL_FUNCTION_SINGLE_VECTOR etc IPI is one of the main remaining
> > cause of vmexits observed in product environment which can't be
> > optimized by PV IPIs. This patch is the follow-up on commit
> > 0e6d242eccdb (KVM: LAPIC: Micro optimize IPI latency), to optimize
> > redundancy logic before fixed mode ipi is delivered in the fast
> > path.
> >
> > - broadcast handling needs to go slow path, so the delivery mode repair
> >   can be delayed to before slow path.
>
> I agree with this part, but is the cost of the irq->shorthand check
> really measurable?

I can drop the second part for v2.

    Wanpeng