general vs fixed counters

[Nichols Romero]

Hi,

I was looking at the CYCLE STALL group:
https://github.com/RRZE-HPC/likwid/blob/master/groups/ICX/CYCLE_STALLS.txt

which uses INST_RETIRED.ANY

I also looked at a list of HW events as produced by VTune:
INST_RETIRED.ANY_P Number of instructions retired. General Counter - architecture event INST_RETIRED.ANY Number of instructions retired. Fixed Counter - architectural event

After reading this page: https://github.com/RRZE-HPC/likwid/wiki/Skylake#fixed-purpose-counters

I still don't quite understand why I would want to use ANY (fixed) vs. ANY_P (general). Mostly because I just don't understand the suboptions for the counter.

What's the main difference?

Thanks,

[Thomas Gruber]

Hi,

I think the main difference is that you can use PEBS (precise event-based sampling) with the general-purpose counters, commonly with PMC0 only.

Best,
Thomas