53 lines
2.2 KiB
YAML
53 lines
2.2 KiB
YAML
---
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features:
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- |
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The libvirt driver now supports booting instances by asking for virtual
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GPUs.
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In order to support that, the operators should specify the enabled vGPU
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types in the nova-compute configuration file by using the configuration
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option ``[devices]/enabled_vgpu_types``. Only the enabled vGPU types can be
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used by instances.
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For knowing which types the physical GPU driver supports for libvirt, the
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operator can look at the sysfs by doing
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..
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ls /sys/class/mdev_bus/<device>/mdev_supported_types
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Operators can specify a VGPU resource in a flavor by adding in the flavor's
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extra specs
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..
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nova flavor-key <flavor-id> set resources:VGPU=1
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That said, Nova currently has some caveats for using vGPUs.
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* For the moment, only a single type can be supported across one compute
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node, which means that libvirt will create the vGPU by using that
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specific type only. It's also possible to have two compute nodes having
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different types but there is no possibility yet to specify in the flavor
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which specific type we want to use for that instance.
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* For the moment, please don't restart instances (or suspend/resume them)
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or the VGPU related device will be removed from the guest.
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* Mediated devices that are created by the libvirt driver are not persisted
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upon reboot. Consequently, a guest startup would fail since the virtual
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device wouldn't exist. In order to prevent that issue, when restarting
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the compute service, the libvirt driver now looks at all the guest XMLs
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to check if they have mediated devices, and if the mediated device no
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longer exists, then Nova recreates it by using the same UUID.
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* If you use Nvidia GRID cards, please know that there is a limitation with
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the nvidia driver that prevents one guest to have more than one virtual
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GPU from the same physical card. One guest can have two or more virtual
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GPUs but then it requires each vGPU to be hosted by a separate physical
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card.
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We are working actively to remove or workaround those caveats, but please
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understand that for the moment this feature is experimental given all the
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above.
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