A characterization of processor performance in the VAX-11/780

This paper reports the results of a study of VAXllR80 processor performance using a novel hardware monitoring technique. A micro-PC histogram monitor was buiit for these measurements. It kee s a count of the number of microcode cycles execute z ( at each microcode location. Measurement ex eriments were performed on live timesharing wor i loads as well as on synthetic workloads of several types. The histogram counts allow the calculation of the frequency of various architectural events, such as the frequency of different types of opcodes and operand specifiers, as well as the frequency of some im lementation-s ecific events, such as translation bu h er misses.?p he measurement technique also yields the amount of processing time spent, in various activities, such as ordinary microcode computation, memory management, and processor stalls of different kinds. This paper reports in detail the amount of time the “average ’ VAX instruction spends in these activities. 1.