I intend to get some iCache/dCache stats using the PMC capabilities of
MPC750 (MMCR0/1 and PMCn registers, using mfspr and mtspr instructions).
I went on to add some helper functions to set and get PMC[2,3] counters on
MPC750, until I realized that there are pmc_control() and pmc_get_info()
system calls for the same. There were no man pages for this, and I realized
that these system calls will only function if the kernel is built with
PERFCTRS. In fact, the pmc_xxx() helper functions for powerpc don't seem to
be defined at all-- or at least I can't find it in the source. Allen Briggs
seems to have done this work for Intel XScale, but I am not sure if this
work was ever completed for PowerPC platforms.
Are these system calls (pmc_control and pmc_get_info) baked at all? If they
are, are there any useful examples/docs to refer to? If not, do I just go
ahead on the path of custom code to get/set PMC[2,3]? I am specifically
interested in iCache/dCache misses etc., which seem to be captured in PMC2
and PMC3 respectively.