From: Alex Williamson <alex.williamson@redhat.com>
To: Yang Zhong <yang.zhong@intel.com>
Cc: qemu-devel@nongnu.org, xiaoguangrong.eric@gmail.com,
ehabkost@redhat.com, pbonzini@redhat.com, anthony.xu@intel.com
Subject: Re: [Qemu-devel] [PATCH 0/2] add "nopin" option in the memory-backend-file
Date: Mon, 16 Oct 2017 09:47:54 -0600 [thread overview]
Message-ID: <20171016094754.0ba814c1@t450s.home> (raw)
In-Reply-To: <1508144183-30844-1-git-send-email-yang.zhong@intel.com>
On Mon, 16 Oct 2017 16:56:21 +0800
Yang Zhong <yang.zhong@intel.com> wrote:
> Qemu does not need pin NVDIMM memory for VFIO device during VFIO
> hotplug, what's more, if there is no NVDIMM hw in the test machine,
> the VFIO hotplug operation will need at least 10 minutes to pin RAM
> as the NVDIMM, this time is not accepted. So we add "nopin=on" option
> in the memory-backed-file, which can avoid to pin RAM memory for NVDIMM.
>
> The new command like below:
> -object memory-backend-file,id=mem0,share,nopin=on,mem-path=kvm.img,size=9161408512
>
> The default of "nopin" still "off" value, which is same with previous value.
If an NVDIMM is not a possible DMA target for a VFIO assigned device
then it should be in a different AddressSpace from the device. If an
NVDIMM can be a DMA target then it's the correct thing to do to pin it
through the IOMMU for a VFIO device even if it might take considerable
time to do so. Thanks,
Alex
prev parent reply other threads:[~2017-10-16 15:48 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-16 8:56 [Qemu-devel] [PATCH 0/2] add "nopin" option in the memory-backend-file Yang Zhong
2017-10-16 8:56 ` [Qemu-devel] [PATCH 1/2] hostmem-file: Add "nopin" option for memory-backend-file Yang Zhong
2017-10-16 8:56 ` [Qemu-devel] [PATCH 2/2] nvdimm: Add "nopin" for related documents Yang Zhong
2017-10-16 10:20 ` [Qemu-devel] [PATCH 0/2] add "nopin" option in the memory-backend-file Xiao Guangrong
2017-10-16 11:58 ` Paolo Bonzini
2017-10-18 5:57 ` Zhong Yang
2017-10-18 9:48 ` Paolo Bonzini
2017-10-18 9:56 ` Zhong Yang
2017-10-18 5:34 ` Zhong Yang
2017-10-16 15:47 ` Alex Williamson [this message]
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