PCI passthrough allows VNFs to direct access to physical PCI devices.
They appear and act as if they are physically attached to the VNF.
This technology can be used to map a physical NIC directly to a single VNF.
PCI passthrough can offer many performance advantages:
- Exclusive one to one mapping
- Bypass the hypervisor
- Direct access to I/O resources
- Reduced CPU utilisation
- Reduced system latency
- Increased I/O throughput
The disadvantage to PCI passthrough is the entire physical NIC is dedicated to a single VNF and can not be used by other VNFs. It means the number of VNFs that can take advantage of this performance benefit is limited to the number of physical NICs on a system