[libvirt-users] nvme, spdk and host linux version

Mauricio Tavares raubvogel at gmail.com
Thu Dec 12 14:51:00 UTC 2019

On Thu, Dec 12, 2019 at 5:40 AM Michal Privoznik <mprivozn at redhat.com> wrote:
> On 11/27/19 4:12 PM, Mauricio Tavares wrote:
> > I have been following the patches on nvme support on the list and was
> > wondering: If I wanted to build a vm host to be on the bleeding edge
> > for nvme and spdk fun in libvirt, which linux distro --
> > fedora/ubuntu/centos/etc -- should I pick?
> >
> For NVMe itself it probably doesn't matter as it doesn't require any
> special library. However, I'm not so sure about SPDK, esp. whether my
> NVMe patches is what you really need? My patches enable the only missing
> combination:
> host kernel storage stack + qemu storage stack = <disk type='block>
> <source dev='/dev/nvme0n1'/> </disk>
>    This has disadvantage of latency added by both stacks, but allows
> migration.
> neither host kernel nor qemu storage stack = <hostdev/> (aka PCI assignment)
>    This offers near bare metal latencies, but prohibits migration.
> qemu storage stack only = <disk type='nvme'/>
>    This is what my patches implement and should combine the above two:
> small latencies and ability to migrate.
      That is actually my question: is handing the hard drive through
PCI assignment faster or slowe than disk type='nvme'?

> Michal

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