linux-kernel - Re: [PATCH 3/5] KVM: ensure pool time is longer than block

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Date:   Fri, 1 Nov 2019 19:16:26 -0200
From:   Marcelo Tosatti <mtosatti@...hat.com>
To:     Zhenzhong Duan <zhenzhong.duan@...cle.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        joao.m.martins@...cle.com, rafael.j.wysocki@...el.com,
        rkrcmar@...hat.com, pbonzini@...hat.com
Subject: Re: [PATCH 3/5] KVM: ensure pool time is longer than block_ns

On Sat, Oct 26, 2019 at 11:23:57AM +0800, Zhenzhong Duan wrote:
> When (block_ns == vcpu->halt_poll_ns), there is not a margin so that
> vCPU may still get into block state unnecessorily.
> 
> Signed-off-by: Zhenzhong Duan <zhenzhong.duan@...cle.com>
> ---
>  virt/kvm/kvm_main.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 1b6fe3b..48a1f1a 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -2371,7 +2371,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
>  		if (!vcpu_valid_wakeup(vcpu)) {
>  			shrink_halt_poll_ns(vcpu);
>  		} else if (halt_poll_ns) {
> -			if (block_ns <= vcpu->halt_poll_ns)
> +			if (block_ns < vcpu->halt_poll_ns)
>  				;
>  			/* we had a short halt and our poll time is too small */
>  			else if (block_ns < halt_poll_ns)
> -- 
> 1.8.3.1

Makes sense.