Fault tolerant patent application for virtual machine

[0018]For incoming network packets, the following is done during the logging mode. When a packet is received, an event-request is posted for the VMM, at Block 210. When the VMM processes the event, it stops the VM, synchronizes the guest VCPU state, and then calls into the device emulator (i.e., device emulation software event handler), at Block 220. The device emulator logs an event at Block 230. Then, the device emulator receives the packets, and logs their contents, at Block 240. The last packet logged is marked so that during replay the device emulator can know when the last packet for this event occurs in the log.

[0019]During replay the following occurs: When an I/O event is encountered in the log, the device emulator (i.e., device emulation software event handler) is called by the VMM. The device emulator reads all packets that were logged, and copies them into the memory of the VM. In this way, the receive queue of packets is updated at the exact same point in the instruction execution sequence during logging and replay.

United States Patent Application 20090007111
Kind Code A1
Nelson; Michael ;   et al. January 1, 2009

LOGGING AND REPLAYING INPUT/OUTPUT EVENTS FOR A VIRTUAL MACHINE

VMWARE application.