IPF_HZ_MULT
#define IPF_TTLVAL(x) (((x) / IPF_HZ_MULT) * IPF_HZ_DIVIDE)
(hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT,
callout_reset(&softc->ipf_slow_ch, (hz / IPF_HZ_DIVIDE) * IPF_HZ_MULT,