Method for performing hierarchical hang detection in a computer system

Abstract

A method of detecting a hang in a computer system, by generating a plurality of hang strobe signals, detecting that a hang has occurred in the computer system using the hang strobe signals, and determining whether the hang occurred in the processing unit or in the memory subsystem. The intervals of the hang strobe signals may be programmably set. The first hang strobe signal (for the processing unit) preferably has an interval that is longer than the second hang strobe signal (for the memory subsystem). More than two strobe signals may be provided, e.g., for additional access layers of the memory subsystem. Hang detection may be accomplished in part by calculating a number of hang pulses that have issued during pendency of a processor instruction, and then selectively comparing the number to one of two hang limit values respectively associated with the processing unit and the memory subsystem. This selection may be based on a signal indicating whether any requests are still pending in the memory subsystem. The hang limit values can also be programmably set.

Dependencies are inferred from the claim text.