Impact: extend performance counter support on x86 Intel CPUs
Modern Intel CPUs have 3 "fixed-function" performance counters, which
count these hardware events:
Instr_Retired.Any
CPU_CLK_Unhalted.Core
CPU_CLK_Unhalted.Ref
Add support for them to the performance counters subsystem.
Their use is transparent to user-space: the counter scheduler is
extended to automatically recognize the cases where a fixed-function
PMC can be utilized instead of a generic PMC. In such cases the
generic PMC is kept available for more counters.
The above fixed-function events map to these generic counter hw events:
PERF_COUNT_INSTRUCTIONS
PERF_COUNT_CPU_CYCLES
PERF_COUNT_BUS_CYCLES
(The 'bus' cycles are in reality often CPU-ish cycles, just with a fixed
frequency.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2f18d1e8d0