This is xnu-8019. See this file in:
Directory listing for xnu-8019//osfmk/kperf
Makefile
action.c
action.h
ast.h
buffer.h
callstack.c
callstack.h
context.h
kdebug_trigger.c
kdebug_trigger.h
kperf.c
kperf.h
kperf_kpc.c
kperf_kpc.h
kperfbsd.c
kperfbsd.h
kptimer.c
kptimer.h
lazy.c
lazy.h
meminfo.c
meminfo.h
pet.c
pet.h
sample.h
task_samplers.c
task_samplers.h
thread_samplers.c
thread_samplers.h