linux-kernel - Re: [PATCH v7 2/3] KVM: dynamic halt-polling

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Message-ID: <BLU436-SMTP237F3D6EFE0CCEE884C904780570@phx.gbl>
Date:	Sat, 5 Sep 2015 06:38:41 +0800
From:	Wanpeng Li <wanpeng.li@...mail.com>
To:	Paolo Bonzini <pbonzini@...hat.com>
CC:	David Matlack <dmatlack@...gle.com>, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 2/3] KVM: dynamic halt-polling

Hi Paolo,
On 9/3/15 10:07 PM, Wanpeng Li wrote:
> [...]
>   static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
>   {
>   	if (kvm_arch_vcpu_runnable(vcpu)) {
> @@ -1928,7 +1962,8 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
>   {
>   	ktime_t start, cur;
>   	DEFINE_WAIT(wait);
> -	bool waited = false;
> +	bool polled = false, waited = false;
> +	u64 poll_ns = 0, wait_ns = 0, block_ns = 0;
>   
>   	start = cur = ktime_get();
>   	if (vcpu->halt_poll_ns) {
> @@ -1940,11 +1975,16 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
>   			 * arrives.
>   			 */
>   			if (kvm_vcpu_check_block(vcpu) < 0) {
> +				polled = true;
>   				++vcpu->stat.halt_successful_poll;
> -				goto out;
> +				break;
>   			}
>   			cur = ktime_get();
>   		} while (single_task_running() && ktime_before(cur, stop));
> +
> +		poll_ns = ktime_to_ns(cur) - ktime_to_ns(start);
> +		if (polled)
> +			goto out;
>

Please move poll_ns caculation under if() when you applied, as I 
explained in reply to v6.

Regards,
Wanpeng Li
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