This disclosure relates to the field of hardware emulation solution called c-UX (code named Kiran) which runs HPUX in emulated (Itanium hardware emulation on x86) mode as a futuristic solution for the margin rich UNIX business. The value of containerized HPUX is that it allows customers using legacy HPUX applications to continue running on x86 hardware. c-UX design relies on instruction level emulation which has inherent performance issues. Especially, compute intensive workloads are prone to performance issues while running in emulated environment. However, I/O workloads on such emulated systems can make use of direct device access or device assignment when configured for the highest possible I/O performance. This technique provides the most efficient way to do I/O, compared to other approaches such as device emulation, which imposes a high number of exits from guest context, with the benefits of significantly reduced latency, higher bandwidth, and direct use of bare-metal device drivers. The proposal presents an innovative approach to realize Direct I/O mechanism (a.k.a PCI passthrough) on emulated HPUX environment by leveraging Virtual Function I/O framework in Linux. Disclosed is an approach of accelerating I/O performance in c-UX application by allowing the emulated HPUX Operating System direct access to parts of the I/O subsystem of the host and handle various aspects of the communication like DMA and interrupts. It also throws light on the network I/O performance improvement that is achieved on c-UX, using this method.

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