- Run pmcstat -P in top-mode against a spinning process using 15 spinning
threads on a 16 core machine. After a few seconds the sampling stops.
- I added debug printfs (not shown in the diff) to verify that both cases
happened with both IAF (CPU_CLK_UNHALTED_REF) and IAP (UOPS_RETIRED.ALL)
counters on a dual-socket system with E5-2643 CPUs.