Yes, PMCs (CPU performance monitoring counters; also known by many other terms, such as PMU counters, PICs, CPCs, etc). In the past I've written tools that prin

Yes, PMCs (CPU performance monitoring counters; also known by many other terms, such as PMU counters, PICs, CPCs, etc). In the past I've written tools that print usage of memory busses (really, CPU interconnect ports) via the PMCs. They are also a PITA to work with. As another person said, it shows up as CPU utilization. So I check that along with IPC (instructions per cycle), and if IPC is low (what "low" is depends, but say, < 1.0), then that's a good clue you're blocked on memory. ... but of course, I want actual throughput (usage), bandwidth (maximum), and utilization (ratio), which is more digging with the PMCs.