KTR_SCHED broken ?

Hi,

root_at_gw:~/RTBench-0.1/results #> sysctl debug.ktr
debug.ktr.alq_enable: 1
debug.ktr.alq_file: /tmp/ktr.out
debug.ktr.alq_depth: 32768
debug.ktr.alq_failed: 0
debug.ktr.alq_cnt: 0
debug.ktr.alq_max: 0
debug.ktr.clear: 0
debug.ktr.version: 2
debug.ktr.entries: 32768
debug.ktr.compile: 536870912
debug.ktr.mask: 536870912
debug.ktr.cpumask: -1

daffy_at_gw:~ %> ll /tmp/ktr.out
-rw-------  1 root  wheel     0B Jul 17 21:13 /tmp/ktr.out

root_at_gw:~ #> ktrdump -ct
index  cpu timestamp        trace
------ --- ---------------- -----

nothing...

[FROM MY KERNCONF]
options KTR
options ALQ
options KTR_ALQ
options KTR_ENTRIES=32768
options KTR_COMPILE=KTR_SCHED
options KTR_MASK=KTR_SCHED
[EOF]

While KTR_INTR works, it seems that KTR_SCHED does not or maybee  
there is a magic sause ?
Best regards,
--
Olivier Warin