Display PCI stats in Horizon per Compute as we do CPU/Memory

Summary
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Display PCI Resource history in Horizon

Motivation
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As more Accelerated device support is given to OpenStack it is tough to maintain and plan without the resource utilization info on Horizon. All the devices are taken as Pci Passthrough devices but there is currently no way to check on teh resource utilization of the same.

Description
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This blueprint talks about showing the Pci resource stats along with cpu/memory stats that are shown on the Horizon admin/hypervisor tab.
With more Accelerated Device support coming in Openstack like GPU,FPGA,QAT, SR-IOV, we should have a way to display the current usage details in the Horizon. Currently all the above are detected as pci devices but there is no way to check on the status of each apart from going in each Compute and checking nova-compute.log. This is not robust and hampers in planning of the instances. Also there is no aggregate view of all the available PCI devices in the datacenter which can be used to plan the instances better.

Proposed Change
===============

The change will affect the navaclient and nova api of getting hypervisor stats and also Horizon to display the stats properly.

UX
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There should be support on the Horizon to display Pci Stats per Hypervisor.

Testing
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To be planned.

Outside Dependencies
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To be analyzed.

Requirements Update Required
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Yes, we need to update the requirements one more formal discussion are started on this.

Doc Impact
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Only documnet that Pci stats are displayed giving the current free count.