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Generic PCI Resource

https://bugs.launchpad.net/ironic-inspector/+bug/1580893

Currently, the iLO driver sets a GPU resource capability by hardware inspection (namely pci_gpu_devices¹). In this spec, we want to propose a more generic implementation of hardware inspection and updating the node capabilities. The name of the capability, as well as the PCI vendor and device ID list will be configured by the deployer. After creating a corresponding flavor, nova scheduler can filter nodes by flavor's extra_specs for a wide range of PCI device types.

Problem description

Some workloads may require presence of specific hardware. An example of this can be an image flavor, which requires a minimal set of hardware accelerators to be present in order to be effective. Another flavor may require a different accelerator in a differing quantity. The HP iLO driver supports updating the capability list with a number of present GPUs, which demonstrates, that the feature is in demand for customers using that specific hardware. A more general support of various hardware is also in demand, to accommodate new solutions, which are entering the market².

Proposed change

The proposed change is to implement a collector of PCI devices in the ironic-python-agent inspector module, which will return a full list of PCI devices to ironic inspector.

The list will consist of dicts containing vendor_id and product_id fields:

hw_info['pci_devices'] = [{'vendor_id': '8086', 'product_id': '0412'},
                          {'vendor_id': '8086', 'product_id': '2955'}]

The second part of the change is to write an ironic inspector plugin, which updates nodes with configured properties for use by the nova scheduler.

The ironic-inspector configuration will include a list of capability names with their corresponding vendor and device IDs. Each defined capability will behave the same way as the pci_gpu_devices capability in the iLO driver.

The configuration option will be identical with the pci_alias PCI passthrough configuration option in nova³:

pci_alias={"vendor_id":"8086", "product_id":"1520", "name":"pci_gpu"}

It's possible to configure multiple pci_alias by having them each separate on their own config line:

pci_alias={"vendor_id":"8086", "product_id":"0412", "name":"pci_gpu"}
pci_alias={"vendor_id":"8086", "product_id":"2955", "name":"pci_vca"}

Several vendor/product IDs can be mapped to the same name. This can be used in case the operator determines they serve an equivalent function.

The capabilities are then read by nova scheduler and used for filtering, by matching against flavor's extra_specs.⁴

Alternatives

One alternative is to use the iLO driver, which supports pci_gpu_devices extra capability, but it doesn't support other PCI devices. Another alternative is to manually update the node capabilities, without the ironic-inspector. This may be a valid solution if all instances of the new hardware are configured in the same way.

Implementation

Assignee(s)

Primary assignee:: xek
Other contributors:: szymon-borkowski

Work Items

create a tooling module for listing PCI devices

implement a collector of PCI devices in ironic-python-agent inspector module

implement an ironic inspector plugin, which updates node properties with configured PCI resource capabilities for use by nova scheduler

document the new feature

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