From: Zenghui Yu <yuzenghui@huawei.com>
To: Marc Zyngier <maz@kernel.org>, <kvm@vger.kernel.org>,
<kvmarm@lists.cs.columbia.edu>,
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 2/2] KVM: arm64: Opportunistically turn off WFI trapping when using direct LPI injection
Date: Fri, 8 Nov 2019 17:20:15 +0800 [thread overview]
Message-ID: <3ca03337-2a10-4958-c551-721461dc0082@huawei.com> (raw)
In-Reply-To: <20191107160412.30301-3-maz@kernel.org>
Hi Marc,
On 2019/11/8 0:04, Marc Zyngier wrote:
> Just like we do for WFE trapping, it can be useful to turn off
> WFI trapping when the physical CPU is not oversubscribed (that
> is, the vcpu is the only runnable process on this CPU) *and*
> that we're using direct injection of interrupts.
>
> The conditions are reevaluated on each vcpu_load(), ensuring that
> we don't switch to this mode on a busy system.
>
> On a GICv4 system, this has the effect of reducing the generation
> of doorbell interrupts to zero when the right conditions are
> met, which is a huge improvement over the current situation
> (where the doorbells are screaming if the CPU ever hits a
> blocking WFI).
>
> Signed-off-by: Marc Zyngier <maz@kernel.org>
Reviewed-by: Zenghui Yu <yuzenghui@huawei.com>
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next prev parent reply other threads:[~2019-11-08 9:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-11-07 16:04 [PATCH 0/2] KVM: arm64: Reduce occurence of GICv4 doorbells on non-oversubscribed systems Marc Zyngier
2019-11-07 16:04 ` [PATCH 1/2] KVM: vgic-v4: Track the number of VLPIs per vcpu Marc Zyngier
2019-11-08 9:20 ` Zenghui Yu
2019-11-07 16:04 ` [PATCH 2/2] KVM: arm64: Opportunistically turn off WFI trapping when using direct LPI injection Marc Zyngier
2019-11-08 9:20 ` Zenghui Yu [this message]
2019-11-07 16:56 ` [PATCH 0/2] KVM: arm64: Reduce occurence of GICv4 doorbells on non-oversubscribed systems Christoffer Dall
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