Method and system for instruction trace reconstruction utilizing performance monitor outputs and bus monitoring

Abstract

A method and system for instruction trace reconstruction utilizing performance monitor outputs and bus monitoring. Performance projections for processor systems and memory subsystems are important for a correct understanding of work loads within the system. An instruction trace is generally utilized to determine distribution of instructions, identification of register dependencies, branch path analyzes and timing. One well known technique for reconstructing an instruction trace can be accomplished by monitoring bus traffic to determine instruction addresses, data addresses and data during the trace, if the initial architectural state of the system is known. The difficulty in reconstructing an instruction trace from monitored bus traffic can be decreased substantially if more definitive information regarding the actual instruction sequence can be obtained. To this end, an internal performance monitor within the processor system is utilized to generate an output each processor clock cycle which is indicative of the exact number of instructions which were executed during that clock cycle, an indication of whether or not a branch instruction was taken or not taken, an offset for each interrupt vector which has been taken, the number of data cache misses, the number of instruction cache misses, the number of store conditional instructions which were executed and the number of store conditional instructions which failed. This information, in combination with monitored bus traffic may be utilized to efficiently and accurately reconstruct an instruction trace without adversely affecting performance of the system under test.

Dependencies are inferred from the claim text.