Raytheon Company

Matthew A Taylor

Gregory Price

John R Wagner

William Wysocki

Chad D McConnell

Techniques are disclosed for interposing on nondeterministic events during multicore virtual machine (VM) execution to capture information that allows for deterministically recreating the nondeterministic events during execution replay of the VM. A method may include reading, by a virtual processor running within a multicore VM instance, an instruction to execute, and, responsive to a determination that the instruction is a nondeterministic instruction, interposing on the nondeterministic instruction execution so as to allow deterministic execution of the nondeterministic instruction during replay execution of the multicore VM instance. Interposing on the nondeterministic instruction execution may include recording a partial barrier event and/or a full barrier event. The nondeterministic instruction may be a read memory access instruction or a write memory access instruction.

Deterministic execution replay for multicore systems

A method for deterministic clock replay can include in response to executing a guest clock access instruction, estimating, using a virtual processor of a guest virtual machine, a value of a guest clock of the guest virtual machine based on (a) a current branch counter value that indicates a number of branch instructions executed since a first time and (b) an average time between execution of branch instructions, comparing the estimated value to an actual guest clock value of a guest clock of the guest virtual machine, and in response to determining the estimated value is less than the actual guest clock value by a threshold value, recording the number of branch instructions, the first time, and the average time between execution of branch instructions in a memory.

Estimation of guest clock value based on branch instruction count and average time between branch instructions for use in deterministic replay of execution

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San Antonio, TX, United States of America

Matthew A Taylor