linux-kernel - Re: [PATCH v2 0/2] KVM: arm64: Optimize the wait for the completion of the VPT analysis

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Date:   Fri, 11 Dec 2020 15:01:39 +0000
From:   Marc Zyngier <maz@...nel.org>
To:     shawnguo@...nel.org, linux@...musvillemoes.dk, leoyang.li@....com,
        mark.rutland@....com, zhiqiang.hou@....com,
        Biwen Li <biwen.li@....nxp.com>, robh+dt@...nel.org,
        tglx@...utronix.de, kvmarm@...ts.cs.columbia.edu,
        Will Deacon <will@...nel.org>, kvm@...r.kernel.org,
        Eric Auger <eric.auger@...hat.com>,
        Christoffer Dall <christoffer.dall@....com>,
        linux-arm-kernel@...ts.infradead.org,
        Suzuki K Poulose <suzuki.poulose@....com>,
        Shenming Lu <lushenming@...wei.com>,
        James Morse <james.morse@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        linux-kernel@...r.kernel.org,
        Julien Thierry <julien.thierry.kdev@...il.com>
Cc:     xiaobo.xie@....com, Hou Zhiqiang <Zhiqiang.Hou@....com>,
        devicetree@...r.kernel.org, Biwen Li <biwen.li@....com>,
        jiafei.pan@....com, yuzenghui@...wei.com,
        wanghaibin.wang@...wei.com
Subject: Re: [PATCH v2 0/2] KVM: arm64: Optimize the wait for the completion of the VPT analysis

On Sat, 28 Nov 2020 22:18:55 +0800, Shenming Lu wrote:
> Right after a vPE is made resident, the code starts polling the
> GICR_VPENDBASER.Dirty bit until it becomes 0, where the delay_us
> is set to 10. But in our measurement, it takes only hundreds of
> nanoseconds, or 1~2 microseconds, to finish parsing the VPT in most
> cases. What's more, we found that the MMIO delay on GICv4.1 system
> (HiSilicon) is about 10 times higher than that on GICv4.0 system in
> kvm-unit-tests (the specific data is as follows).
> 
> [...]

Applied to irq/irqchip-next, thanks!

[1/2] irqchip/gic-v4.1: Reduce the delay time of the poll on the GICR_VPENDBASER.Dirty bit
      commit: 0b39498230ae53e6af981141be99f4c7d5144de6

Patch 2 will be routed via the KVM/arm64 tree.

Cheers,

	M.
-- 
Without deviation from the norm, progress is not possible.