Intel IXP400 manual Access-Layer Components Performance Profiling IxPerfProfAcc, What’s New

Intel® IXP400 Software

Access-Layer Components: Performance Profiling (IxPerfProfAcc)

API 17

This chapter describes the Intel® IXP400 Software v2.0’s “Performance Profiling API” access- layer component.

17.1What’s New

There are no changes or enhancements to this component in software release 2.0.

However, the Internal Bus PMU registers on the IXP46X network processors are not identical to the Internal Bus PMU registers on the IXP42X product line processors. The IxPerfProfAcc component has not be modified to accomodate the IXP46X network processors Internal Bus PMU registers.

The component detects the IXP46X network processors and returns an error when Bus PMU or Intel XScale core PMU functions are requested. The XCycle utility will operate on both IXP42X product line processors and IXP46X network processors.

17.2Overview

The PerfProf Access module (IxPerfProfAcc) provides client access to the available performance statistics from the Intel XScale core’s PMU and the Internal Bus PMU as well as Xcycle, the idle- cycle counter utilities. These PMUs consist of programmable event counters, event select registers, and previous master/slave registers. Each counter is associated with an event by programming the event select registers.

The different features (Intel XScale core PMU, Bus PMU, and Xcycle) are not to be run at the same time as the PMU-enabling software may use a significant portion of the resources. In addition, the PMU-enabling software runs as an interrupt service routine while Xcycle disables interrupt during startup.

Utilizing only one PMU at a time will minimize the impact of the PerfProf Access module. Furthermore, the specific tasks for each PMU are not to be run in parallel. The PerfProf access layer component reads the registers for counter values, does the relevant calculations and presents the results to the client. All event and clock counters managed by the PerfProf access module are split into two, 32-bit-wide counters, to represent the upper and lower 32 bits of the count.

The access layer component itself will not contain any printf functions. Errors will be handled through error logging, but will store the calculated values in pointers to the output parameters — which can be accessed by the calling client. For the Event and Time sampling features of the Intel XScale core PMU, the results will also be printed to an output file.

Programmer’s Guide	IXP400 Software Version 2.0	April 2005
	Document Number: 252539, Revision: 007	247