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Method for measuring interrupt latency in real time

IP.com Disclosure Number: IPCOM000125671D
Publication Date: 2005-Jun-10
Document File: 2 page(s) / 52K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for measuring interrupt latency in real time. Benefits include improved functionality and improved system performance

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Method for measuring interrupt latency in real time

Disclosed is a method for measuring interrupt latency in real time. Benefits include improved functionality and improved system performance.

Background

              Interrupt latency is the elapsed time from when a hardware (HW) interrupt is issued to when the interrupt service routine (ISR) is executed.                                                                                                                                        

              Conventionally, networking controllers and associated software (SW) have no method for accurately measuring interrupt latency during runtime operation. The link between hardware and software is difficult to measure without external measuring equipment. External measuring equipment is not feasible during normal runtime operation.

Description

              The disclosed method is accurate interrupt latency measurement. When an interrupt is issued, an ISR latency counter begins to increment with each clock cycle that occurs (see Figure 1). The clock rate can be any frequency, but it must be defined to the SW. The counter must by readable via a HW register. 

              When the ISR is executed, SW reads the HW interrupt registers to acknowledge the interrupt. (Additional processing may occur.) If the interrupt is generated by the HW of concern, the SW reads the ISR lat...